Now 2 midrange lean seizures!! My patience is running thin!!!!

[YFZRob]

Okay, here's the combo....

Freshly rebuilt bottom end w/ rebuilt crank, all done by ESR.
ESR 310 kit with TRX-7 porting
Keihin PWK 38mm A/S carb from ESR
ESR TRX-5 pipe
CR250 reed block w/ intake boot
pump gas dome in ESR head (only saw 165 psi two days ago)
no air box lid
Uni filter

Okay, originally (about 8 weeks ago), I had a lean seizure. After tearing everything down, practically to the bare frame, I discovered the stock radiator had quite a bit of dirt and mud build up that was almost unnoticeable without the radiator off the quad. So, my assumption was the seizure was from an overheat. I am running the A/S carb with the jetting that ESR sent except for the main.... 50 pilot, 4th clip on DGH needle, 185 main (190 is what came in it). I had done proper WOT plug chops and the plug was dark brown. I never got the chance to do part throttle plug chops. The quad rode great when blasting around a small area when first broken in (after 4-5 heat cycles). The exhaust was always "damp" with oil and pitch black. The VERY FIRST time I get out in the woods with it, where I spent a lot of time in the midrange, the motor seized. Well, as I mentioned above, I thought it was from an overheat due to the radiator. I got the jug bored by ESR and a new piston slapped in.

After breaking it in (this time I went back to the 190 to start), I did plug chops at WOT (not realizing that needle setting may have caused the seizure). The 190 showed a good bit rich.....pretty much black. I rode the quad on a motox track for over an hour, as well as about an hour spent the day I did the WOT plug chops. No problems at all. Yesterday I went out in the woods for the first time on the 2nd build. Less than 10 minutes down the trail, fresh off the trailer, the motor seized!! :mad: I installed a temp gauge this time too, and had consistent 180-190 temps.

SO, now that cooling issues are ruled out, the motor DEFINITELY leaned out. Since the main jet isn't the issue, it's the needle or pilot. So, instead boring my motor for a 2nd time (leaving me with just one bore left), I am going to just drop another chunk of change with ESR on a new 310 cylinder w/ the same TRX-7 porting and new piston.

Anyone want to buy my existing ESR 310 cylinder??? It'll be bored to 72.5 mm...it's at 72.2 now.

My question is....either the 50 pilot and/or DGH needle has to be the problem. Has anyone ever run a richer needle than a DGH? I cannot imagine the motor seizing over just one clip position, meaning, I don't know if the same needle on the 5 position would actually be safe. I know to do part throttle plug chops this time, but seeing how the motor seized in only 10 minutes, it may be dangerous to simply do plug chops. Anyway, I am going to jump up to a 58 pilot (since 50 seems small to me), and see if ESR has a suggestion to a richer needle. Anyone have any suggestions??? Thanks in advance!

[zedicus00]

im running a 57 pilot with that needle in the middle clip and a 200 main and im at around 3000ft elevation. in a short 38 A/S dirtbike carb.

how much you want for that 310 kit?

[YFZRob]

Thanks for the suggestions! Correct me if I'm wrong....you run less fuel with increased elevation? If that's the case, then I am extremely lean by comparison to you, with the exception of the needle. What motor?

The 310 kit would just be the ESR cylinder...nothing more. I would be willing to sell it for $200....all it needs is a $50 bore, but you'll only have one more bore on it after that according to ESR. I don't know what a bare ESR ported cylinder would be new....I'm gonna find out today :ermm: Seeing how a new 310 kit is $949 with full porting, deduct the cost of the head, $250 and piston $139, and gaskets $30-40, it leaves the cost of a new one around $520.00.

[zedicus00]

for 200 i would take it. and yes as elevation goes up u use less fuel. i am running a 300cc standard cylender right now. do you take paypal and is that shipped?

[YFZRob]

I'll do $210 shipped. I can get it out today or tomorrow. Paypal me at rob@looseboltsmotorsports.com.

[zedicus00]

o and yes its sounds like you are way lean. im jetted just a hair rich on low end and topend my midrange is about right.

[zedicus00]

i jus sent it anyways. get that sent out tonight if at all possible. thanx!

[beerock]

umm, i dunno wtf is goin on bt a 200 on a stock jug? a 57 pilot?I'm at sea level and run a dgh with a 55 pilot,185 main on a 330.

and sparks said to go to a 50-52 and run a cel needle

the pilot has nothing to do with the midrange its from idle up to 1/4 throttle.

The dgh needle in the middle clip IS a VERY RICH needle.
WHEN is the last time you did a leak down test??????

it sounds like you have a intake leak, main seal leak etc...
if you keep seizing them your not checking your plugs correctly. the 2 strokes just dont UP and seize. there are tell tale signs when its going to. have you been putting NEW plugs in for each plug chop?

You need to do a leak down test and make sure it holds if esr built it then they are liable.

[YFZRob]

A crank seal leak was what I first assumed the problem was. The entire bottom end was all original. So, when the first lean seizure occured, I sent everything to ESR. They rebuilt the crank, installed new bearings and oil seals in the case halves, and reassembled with new gaskets. I am not firing this engine until I do a couple leak down tests. This WILL NOT happen again. When I did plug chops, it was on fresh plugs. 185 and 190 mains were fine.....what I didn't do right was part throttle chops. Like I mentioned, WOT was fine.....no issues at all. Hell, I had gone through 3-4 gallons of gas without any signs of a lean condition. 5-10 minutes into the woods and the motor seizes. The 3-4 gallons of fuel that I had burned were from break-in heat cycles in neutral, about an hour on a motox track, and for plug chops.

When I talked to Jay at ESR about it, he said this happens often. He's had guys drag race all day long and seize their motor on the way back to their truck :confused:. He claims there is a lean spot on the DGH needle, and the needle they are using above this (which he didn't tell me which part number) is a tad rich down low, but doesn't seem to have the same lean spot around 1/2 throttle of the DGH needle.

There is nothing abnormal about the way the motor runs. It screamed up until the second it seized. I am almost hoping I find a leak.....something to prove a better explanation than simply jetting.

[lil400exman]

Sounds like an air leak to me. Do a leak down test and see your results.;)

Let us know what happens!

[YFZRob]

On the top-end, where are typical air leaks? On the bottom end, where are they??

I am very meticulous about building the top end. All gasket surfaces are free of debris and old gasket. I NEVER resuse gaskets, and I torque everything to the factory specs or slightly over. I also wipe down all gasket surfaces with brake parts cleaner prior to install so there isn't any left over residue/oils. I do not use any additives to the gaskets, only dry installs. Since it's a long rod motor, I am using an ESR spacer plate with fresh paper (the green fiber/paper gaskets that ESR supplies) on both sides. I also am using the same gasket on both sides of the reed block. I have a NEW CR250 reed/intake boot with new CR250 clamp at the carb side of the boot. Any other suggestions??? Obviously I am going to test this thing extensively, but proper assembly to begin with is ideal obviously.

[zedicus00]

man u should hav ZERO air leeks i would think. i couldnt get the reed gasket to fit over my larger reed so there isnt a gasket on 1 side of my reed. my water pump is dun with rtv silicone. that type of stuf fis how my entire engine is dun. and i hav 0 air leeks.... im gunna hafta say its in yur jetting. start with sumthing that should be very rich and work backwards. also i juet for a slightly righ low speed setup, it has never failed me.

[beerock]

Originally posted by zedicus00
man u should hav ZERO air leeks i would think. i couldnt get the reed gasket to fit over my larger reed so there isnt a gasket on 1 side of my reed. my water pump is dun with rtv silicone. that type of stuf fis how my entire engine is dun. and i hav 0 air leeks.... im gunna hafta say its in yur jetting. start with sumthing that should be very rich and work backwards. also i juet for a slightly righ low speed setup, it has never failed me.

DUDE CAMON, trim the gasket to fit the reed cage, YOUR ASKIN for trouble...


2nd.

the dgh has no lean condition..... its actually a VERY rich needle. check the charts and look...........

besides sparks runs a CEL needle with there 330's!! and the cel is very lean compared to a DGH

[YFZRob]

Well, I don't know where ESR is coming up with this stuff. After I do a leak down, what do you suggest if I find the motor to be air leak free??

[250-R-250]

Its hard to say..I dont think there is too much else to do after the tests enless you want to tear the whole thing down.....I say if you trust ESR.....have a new carb.....and your bottom end is good....Put it on and have some fun.....It sucks when this happens I know...BTW...Does ESR Back up there Kits?

Best of Luck

[zedicus00]

[QUOTE]Originally posted by beerock
[B]DUDE CAMON, trim the gasket to fit the reed cage, YOUR ASKIN for trouble...


i cant it was one of thouse metal lined gaskets or i would hav trimmed it.

i would pt it to gether an run it. if it seems lean richen it up, or run it WOT.

[beerock]

make sure the top of the carb is tight if its not it can lean it out. also check the intake, but then again, youll find out when the vac test is done.

but the carb top could be a problem.

[YFZRob]

Its hard to say..I dont think there is too much else to do after the tests enless you want to tear the whole thing down.....I say if you trust ESR.....have a new carb.....and your bottom end is good....Put it on and have some fun.....It sucks when this happens I know...BTW...Does ESR Back up there Kits?

Well, seeing how the same thing happened twice...once on the completely original bottom end, seals and all, then again after the ESR rebuild, I would have to say the bottom end is okay. BUT....coincidence is a b*tch! ESR obviously doesn't back up their prejetted carbs. Even though Beerock stated the fact that the DGH needle is rich, ESR seems to think it has a lean spot, YET they don't tell you this when you buy a complete 310 top end including the carb at the same time. Seeing how I am now on my 3rd piston in about 5 hours of ride time, I wish they'd back up their 310 kits! If I were half assing the install, it'd be different, but I am very meticulous about my work and never reuse ANYTHING.


but the carb top could be a problem.

Very very true!! I never really tighten the carb top with any force, just barely snug. Not sure if any air could be leaking through or what. I double checked to make sure the rubber seal around the inside of the carb top hadn't fallen out. Other than that, there shouldn't be any other issues with the carb since it's new. Do any of you have a washer UNDER the E-clip on the needle? I know some carbs come standard with a washer under it, which would raise it even further. I do not. Not sure it should be there or not. If so, ESR removed it when rejetting the carb. The 39 PWK comes standard with the DGH, not the 38 PWK A/S, so they were at the needle assembly.

[250-R-250]

If you are having second thought on the esr carb....why not go back to a smaller stock carb or one of a cr? Wont that work? Sorry I am not good with carbs....

[Hoppedrap]

I would lean towards an air leak, Im running a 50 pilot, R1366M needle 4th clip and 190 main. 39 pwk on a ESR 350PV but its also 100 degrees here. Orderd a 40.5 pwk from ESR yesterday and they were putting a dgh needle in it which he said was going to be on rich side. If you don't find an air leak call duncan they should be able to help you.

[250R Baja Rider]

I had the same problems a while back. Did all the checks.

Ended up being the gas I was using.

Are you running high octane race gas?
I was told to run the engine on pump gas when in fact the head had been milled for high compression.

After I switched to race gas, problem solved.

[Tom TRX250R]

Rob That sucks man especially cuz that is such a cherry R! From my experience in building motors it sounds like you have an air leak somewhere. There is several spots where it could be leaking but you won't know until you actually do a leak down test on the motor. Though my friend did rebuild his R and ran 100 octane fuel in it and seized the motor after only about an hour or two of riding. After showing him the MacDizzy compression chart he should have been running 110. What fuel are you running with what mix ratio? What size dome are you running and what did ESR suggest as far as fuel octane? Best of luck to ya and don't give up on the R, they are very reliable once dialed in right!

[jcas]

Yep, try higher octane gas. I had a post on here named 87 problems and 87 problems 2. I have almost the same setup as you and had the same problem. I spent $$$$ on bores, piston kits, seals, cdi, wiring harness, stator, gaskets, different needles, and jets. Changed to 110 octane, problem solved!! On the positive side, she runs awesome with all the new parts!

87310R
83R
03 Blaster
81 200 (sold)

[YFZRob]

I think you guys are heading in the right direction! ESR gave me great service this time around. Within 24 hours of receiving the jug, they had it bored and ready to ship with the new parts. I talked with Jay at ESR for quite a while. We resolved the problem to be either A) the stator and flywheel, or flywheel only due to broken magnet, or B) fuel. I am running the pump gas dome, and with a shallow threaded compression tester, only saw 165 psi. Granted the BR9ES has a LOT longer reach than the compression tester, so the compression would have been about 10 psi higher according to Jay, which he claims is still okay on pump gas. BUT, since a lot of you I am assuming were burning up your motors on pump gas, you were probably running a pump gas dome, except Baja Rider (stock head)??? I don't mind running 110 in it at all times as long as it holds together.

Also, Jay suggested that it's either the flywheel's magnets being broken, which would cause incorrect timing, or the fuel octane. After I told him that my piston was melted clear down to the top ring land on the exhaust side, he had these suggestions. He said I was dealing with severe detonation caused by one of these two issues. He went on to say that it wouldn't have been an air leak because the bike ran so well at full throttle. If it was an air leak, it would have burned up faster, expecially with a lot of WOT use. BUT, that doesn't mean I am not going to check for air leaks! He just felt that based on my situation when it finally seized and the damage that occurred, that I either have too low of octane or a timing issue from a bad flywheel.

If I end up finding no air leaks and simply just run 110 all the time, I might as well go up to the race gas dome??

[beerock]

Originally posted by YFZRob


If I end up finding no air leaks and simply just run 110 all the time, I might as well go up to the race gas dome??

might as well more money mo power

[jcas]

That's what I did. You lose the overrev but just gear up to compensate. I just had new clutches with the 89 update done at ESR and the bike was reving out fast with 13/39 gearing. Changed the gearing to 13/38 and I pull away from my dad's 05 450R with ESR full race pipe, jet kit, and airbox eliminator kit. Not bad for an 18 year old bike!

87 310R
83 R
03 Blaster

[YFZRob]

Well, I did some playing around with the head domes. When I first got everything from ESR, I simply grabbed the "PA" part number dome and used it, the P being for pump gas. Well, I am beginning to think they sent me a mislabled dome. I just spent about 15 minutes studying the two domes, the RA and the PA. They look identical to the naked eye. I would think the dome volume differences in the pump gas and race gas domes would be very noticeable to the eye. Does anyone know how much difference there may be in these? The height of the dome is the same and the width of the dome is the same as well. The area that is a difficult section of measure is the taper/angle of the dome from the plug hole down to the base of the dome. Everything that I could do to check/measure this showed little or NO differences.

My experience with 2 stroke head domes is mainly from back in the day when REAL jet skis were made. My JS550 and 650 X-2 both had heads like this with interchangeable domes. I always remember the pump gas dome being noticeably larger than the race gas domes.

The part numbers from the domes are:
720T7255RA and 720T7255PA

In about 2 hours, I'll give ESR a call and discuss this with Jay to get his opinion. This MAY be the problem.

[zedicus00]

for sum unknown reason esr makes there own number instead of labeling them in CC's like EVERY other maker. problem is it is very hard to tell a difference by looking at them. my 18cc "racegas" and 21cc "pumpgas" dome are just barely different from the naked eye and they are from 2 completly different manufacturers.

[YFZRob]

CORRECTION! I found a way to measure the domes. I found a surenge with CC measurements. I fully installed a BR9ES and filled each dome on a level surface to the top of the dome portion. The pump gas took approximately 21 cc vs. the race gas dome which took 18-19 cc to the same level.

Sound correct??

[YFZRob]

Okay, the engine is together and running.

Did a leak down test, longer than necessary just to double check. The engine held 8 psi for 25 minutes! No issues there, and it shouldn't have been an issue before. I stepped up to the race gas dome and am using Sunoco 110 leaded "blue" mixed at 32:1 with Castor 927.

At first fire, the engine had very very little smoke, which worried me. It's no where near being cold here in FL, so the Castor couldn't have separated. I idled with light blips for about 10 minutes. Temp gauge read 140. After shutting it down, I did a quick compression test.... 175 (185 roughly with the BR9ES plug because my compression tester only threads into the dome about 4 threads). Good....about 20 psi more than the initial compression test w/ the pump gas dome. I refired the engine for a minute or two. This time, I had more smoke....more normal amount of smoke.

So, HOPEFULLY this time the motor will hold together with the race gas. I have no air leaks, a very good condition electrical system, and what seems like good jetting (50 pilot, 190 main, DDJ needle on 4th clip). Only time will tell, but this time I will be contantly doing plug chops, at ALL RPMs and loads. WOT plug chops did nothing but confuse me last time. The engine always seemed rich at WOT, but had to be lean at any other throttle........my guess is the lack of octane in pump gas made it run too hot when off the main jet. The main was so big that it gave it enough fuel to not detonate w/ pump gas, but being in the powerband but out of the main was just too lean. Thanks again for all the help on this issue. I'll report back after I start riding it with some load and after doing many many plug chops.

[beerock]

bro ditch the br9es and opt for a br8es, your losing alot of midrange with that plug

honestly you need to get the right compression tester adapter piece so it fits in the hole the PROPER way.

[YFZRob]

You sure an 8 is okay to run on a motor like this? Even Honda's factory plug recommendation on the 88 is a BR9ES. The only reason I run a 9 is because it's ESR's recommendation. I have no qualms running an 8, as long as someone can confirm it's not too hot of a plug on a 50+ HP motor.

I have an adapter than will thread all the way down into the dome like the BRxES plugs do, but in order to use it, I'd have to remove the tank. The ESR cylinder really eats up the space that you have with the stock jug between the tank and the head.

[jcas]

I run a BR9ES per ESR. It's a colder plug. Some people think the higher the number, the hotter the plug, but it's actually higher/colder. Two suggestions: Stay with the 9, and put your needle clip at the bottom (richest) position before you start your chops. Go rich, then work your way down. My 310 with h/c dome, airbox eliminator, trx9 pipe, and 38 a/s is jetted at 185 main, DGH needle at lowest setting, and 50 pilot. Good luck

[beerock]

jcas your entitled to your preference and so is everyone else.
The truth is with the same set up as your motor jcas, and a br8es the br8es plugged motor will spank you. PERIOD. the end, thats all she wrote.

run a 9 if you want, in the long run it will cost you more money(more fouled plugs) less power.It just doesnt make sense.

the way to properly jet a 2 stroke is to do WOT chops until you get the main just right, then you do 1/2-3/4 plug chops. put the needle in the MIDDLE position. if you have to start on the richest clip then your not using the right needle and need to move up or down on needle model.

another thing, I dont ssee the DDJ needle on keihns list?

[YFZRob]

I'll give an 8 a shot, but I'm going to use up my 9s on plug chops. My DDJ needle is on 4th clip, and I'll start there doing 1/2 throttle chops.

I don't know where you got that chart, but it's lacking quite a few of Keihin's needles... Check out this link....

Kehin PWK Jet Needles (http://www.sudco.com/catalog105/116-117.pdf)

[powerslider]

Stay with the 9 plug, I would not run an 8 with the compression your running now. I've run 9's in all my R's for years, no problem with plugs fouling....

[beerock]

rob if you run the br8es do your CHOPS with the br8es, you will burn more gas and make more power.

Call up curtis sparks, lrd ,paul turner etc..

they all run 8's if you run a 9 youll be down on power.

power slider the compression hes running???

hes at average. and with more comp you need a hotter spark.

[jcas]

If the br9es is so bad, why is it the only plug ESR sells? Why is it OEM Honda?? Also, as far as the needle position, ESR also told me that the majority of their motors run the clip at the richest position, and after 1/4 throttle the needle is the most important factor in jetting. All I'm saying beer is that I was in the exact same position as rob and the safest way to go is extremely rich then work your way down. Save some $$$. But maybe I'll call your shop and see what your guys recommend, like I do with ESR

[powerslider]

Originally posted by beerock
rob if you run the br8es do your CHOPS with the br8es, you will burn more gas and make more power.

Call up curtis sparks, lrd ,paul turner etc..

they all run 8's if you run a 9 youll be down on power.

power slider the compression hes running???

hes at average. and with more comp you need a hotter spark.

He is now running an 18cc dome, his compression should be substantually above average.

I don't follow your logic of changing to a hotter plug when he's melting pistons. To each his own.......

[YFZRob]

The only reason I am only seeing around 185 psi now is because the motor has about a 40 minutes of run time on it. I haven't been able to get more than 2 hours on a top end yet to see what it finally reaches once the rings are fully seated. BUT, that is a good point.....I do not want to melt a piston again, and a hotter plug will just raise those chances of it happening again. I am fairly certain octane was to blame on the first two, but I'm still going to be super anal with this one. Once I finally determine that octane was the culprit, I'll possibly try the 8.

[powerslider]

The only compression gauge you can really trust is a Snap-on, I run a 19cc dome in a stock bore at 215 psi. Yours should be higher than that with the 18.