Another Jetting Setup

[EDDYL250R]

Hello All,

After Owning my 88 TRX for 8 years I finally completed a frame up rebuild (and 4k poorer :D ) Well the quad is fully together and about ready for it's re-maiden voyage and shakedown testing.

I require some help on the proper jetting (at least a good setting for the minor engine mods that I added in the rebuild) Before the teardown I had the following mods:

Stock jug with a 10 over bore (wisco piston) approx 10 hours on it
Boysen RAD valve with Carbon Reeds
5 (1") holes in the stock airbox lid
Motion Pro Twist Throttle
Split fire Sparkplug (set to stock gap)
Ran pump gas with 32:1 premix (don't remember what type of oil used, I believe it was bel ray). Also ran it on 110 VP, the quad ran well on both types of fuel.

All other air related items are stock (to include the airbox, inlet tubing, 34mm keihin carb, stock exhaust with Answer Spark Arrestor).

Here is the current setting on the carb with the above mods & settings:

1. Jet Needle (JR1474 S) set to third (3) clip
2. Main Jet: 152
3. Slow Jet: 48
4. Idle Adjustment turned all the way in to the left (toward the front of the quad)
5. Air Screw turned 1 1/8 out from full in.

The quad ran really well with this setting, started cold and hot on 1st or 2nd kick. Good power throughout the rev range. I have ran it from elevations of 0-ft (Pismo), to 4500-ft (Sand Mountain), but mainly between 2000-3500-ft. I plan on tuning mainly for the 2000-3500-ft range and eventually getting jet settings for the other 2 upper and lower elevations. All above were either tails or sand.

With the rebuild I added the following:
1. FMF SST Pipe
2. Turbine II Q Silencer.
3. Uni filter tabs into the holes on the Airbox (total 5).
Current filter is a Uni dual foam.

What I need from the experts on the forum is what should I start with as for jetting & settings. I never had to touch the quad since I originally bought it (no mods until now) so I am not very experienced with PROPER jetting. I have done extensive searches on this forum, but could not find anything for the setup I currently plan on running. (in fact I was getting confused with all the different suggestions that were being given. But that was for different configurations and with problem issues. I just want a good starting point and some suggestion on how to proceed from there.

Any help will be greatly appricated.

Please advise, once I get a good starting point I look forward to getting experience on fine tuning the quad to get it spot on for the riding I plan on doing

CHeers

EddyL.

[EDDYL250R]

Did some more seaches on the forum.....is 152 way too lean?? Stock is 158 and FMF suggests between 158 and 160 on the main. Slow jet looks to be spot on at 48.

Just did a compression test on the quad and it is at 158 psi (max). I would like to see a little more compression, so would like to put a CR head gasket on, but with a 152 main it may be running too lean already. Plug was covered with deposits and dark in color. Will be replacing with a new unit before I start her up after I confirm what jets I should be using.

Ed

[86 Quad R]

the dark plug color that you mention. is it after you done a WOT plug chop or is it dark from overall riding?

[EDDYL250R]

Dark from overall riding. It's mostly a dark gray, not black.

The quad has been sitting for about 2 years. The rear axle bearing went out, and my brother and cousin took it upon themselves to try and fix it. Needless to say I had to buy a new axle and rear carrier. I finally decided to do a complete rebuild (minus the engine, as it already had a top & bottom rebuild with less then 10 hours on top and 20 hours on bottom).

I wanted to make sure that my jetting was alright before I started her up again and begin doing tuning runs. Eventually I plan on getting a 38mm A/S, but will probably have to wait a while as I already spent TOO much on what I did this turn around. (I would post photos, but everytime I try they do not get posted).

Here is everything that had been done on this rebuild:

Bored 10 over with wisco piston
Boysen Rad Valve with Carbon Reeds
Barnett Clutch kit
89 Clutch actuator update
Motion Pro Twist Throttle & Cable
FMF SST Pipe
FMF Turbine Core II Q Silencer
Renthal Handlebar
Renthal Half Waffle Medium Grips
Durablue X33 Rear Axle with Billet Hubs
Durablue Anti-Fade Brake Hub
Durablue Billet Axle Carrier
Steamline SS Brake Line (Red)
Nac's Case Saver (Red)
Nac's E-Brake Blockoff (Red)
Nac's Waterpump Cover (Red)
Nac's Aluminum Rear Brake Mount
Nac's Gray Graphics & Seat Cover
Wicked Products +2 A-Arms (Candy Red)
06 TRX450R Shocks
05 TRX450R Front Brake/hub Assembly
AC Racing Pro-Peg Nerfs with SS pegs
AC Racing Chassis Skid Plate
AC Racing Swingarm Skid Plate
AC Racing Front Bumper
AC Racing Rear Grab Bar
All Chassis & Suspension Bearing Replaced
Laker Custom Plastic (Blue)
ITP 9x9 Baja Rear Rims
ITP 10x5 GP Front Rims
ITP MXR6 19x6x5 Front, 18x9x10 Rear Tires
Alloy Boltz SS Bolt Kit (used only half)
Frame painted Graphite

[EDDYL250R]

Well It looks Like I got the downloading figured out. Here are a couple more.

[EDDYL250R]

Last one for now

[edz250r]

Hey....very nice looking quad. I have a random question for ya. What is the total width of your quad? I have 2+ arms on my R and my quad sits high like yours does judging by how extended your arms are (just like mine). I'm only at 47 inches and thats with 7 inch wide front tires.

[ChvyCruzen]

Eddy - sweet quad! No offense or anything, but I can make out the license plate on your bike. Be careful with releasin info like that bro.

[EDDYL250R]

Thanks,

ChvyCruzen, I appricate the heads up. I noticed it too....but I was'nt too concerned at that bike has been in non-op for the past nine years and it is registered at a differenent address, a P.O. box to boot. But I agree that I should be more careful. I have deleted those photos.

Edz250r, The quad sits right at 46" in the front. 51" in the rear. I was thinking of pulling out the bottom ball joint a inch on both sides to one get bit more camber (or is it caster?) and also get the stance out to 48". But I am a little bit concerned that it will weaken that point a bit as I want to jump the crap out of the quad. I think it is sitting as it is because of the 450r shocks & how Wicked does their A-arms.

Here are some updated pictures of the quad now with a seat and graphics. I started it up yesterday for the first time. Took a few kicks to get gas into the cylinder but it started right up. Looks like the slow jet is running spot on at #48, but it is running a little rich on top (I currently have a #158 main installed), before I had a #152, and the plug was dark in color. What do you guys suggest I go from here? Should I drop down to a #156 and do WOT plug chops? A go down 2 steps at a time (154, 152, 150). I am currently running VP 100 unleaded race gas and BelRay H1R premix at 32:1. Let me know.

Here are the photos

[EDDYL250R]

Another

[EDDYL250R]

Another Angle

[EDDYL250R]

Final Shot

[86 Quad R]

your quad is lookin good. :) nice job.

with the engine at operating temp. do a wot plug chop in the gear that you'll run the most in and see what color it is.

what carb are you currently running?

btw: you really dont need to run the race fuel with the compression you have. you'll be fine on pump gas. 185psi is the cut off on pump gas

[EDDYL250R]

Thanks,

Using the stock 34mm carb for now. Yea I know that I can run pump gas, but I had the race fuel on hand and just put a gallon in to make sure everything is operating ok. Also I do plan on doing the CR head gasket & 38mm A/S upgrade soon (currently @ 160 psi, so it may get near that cut off with the CR gasket).

Of course being in California, we get the worst gas in the Union, and I've heard that they plan to reformulate our gas again to make it even cleaner which will lower it below our current 91 octane level, (happened last time they did this). I guess it all depends on the riding I'm doing at the time. If it trail riding I probably can get away with pump, but if I go to the dunes I may require a little more.

Cheers

EddyL.

[86 Quad R]

the cr gasket should get you up to the 175-85 range. if not then the thinnest layer of the trx 3 layer gasket will.

good luck with it.

[edz250r]

Eddy...I thought about doing the same thing with the ball joints, but Pappy advised me not to since it will weaken that joint and snap it right off if you're doing any jumping at all. My shocks were built for all around riding which is which i have more ground clearance and not much shock sag. I'm thinking about getting them rebuilt so the quad sits lower which would give me more width and stability.
your quad looks great!

[EDDYL250R]

edz250r, Thanks for the props, put alot of effort in the build.

Yea, I was thinking the exact same thing about the ball joints. I also want to keep the a-arms set up for maximum durability. I guess I should have went with the +3 length, as they were the same price, but was a little concerned of the width as I do alot of trail riding. That's why I went with only the +2's and also the Durablue X33 Rear Axle. Right now the front tires are situated almost centered with the rear tires (width wise) with the rear axle set at maximum width, Camber angle is right at 0-deg.

I'm hoping with me on the quad, fully dressed, the front will sag a little bit. Right now it is sitting with a width of 46", with me on it, it should be closer to 48". I'll have to check it.

Cheers

[edz250r]

Yeah, I probably should have gone with +3 arms as well since I never ride in very tight areas. Most/all the riding I do is on old railroad beds and open trails. Rarely am I in the woods.

Word of advice from what I've been told by others...don't make the rear end wider than your front. If your front end is 48" with the sag, then take out the spacer(s) in the axle so you're at 48" as well. Maybe others here disagree with me, but thats what I've been told. I guess it has to do with a narrower front end vs rear being less stable in corners.