Somethings Wrong!!!

[KFX400 RACER]

Well my quad was modded alittle with just a open airbox with kn and a dg silencer with a stock pipe. It has a stock carb and reed valve and found out it is bored to a 254.

Well it ran very good and fine before I did this stuff to it. I put on a fmf fatty pipe that sort of looks like the sparks mx pipe and a fmf power core 2 silencer. I rode it with these two things done and rode fine also.

Then I decided to cut the silencer down to 9 inches since it was way too long stock. Also got a alluminum airbox with no lid and using the same kn air filter. Last thing I did was take out the stock head gasket and put in a cr head gasket.

Tried riding it and the first thing I noticed was that when I shortened the silencer was the packing would not stay in at all and I have to run it without packing. Would this hurt the performance since it ran very good for a little bit but would hesitate on top end at full throttle.

I fouled a spark plug but it was in there for at least over half a year of riding and then put a new BR8ES plug in there and now when I ride it when I try to give any throttle past 1/4 it does not rev. Another thing was that the overflow tank was at the full line but know it is almost overflowing and is almost to the top of the tank.

I have no idea what is wrong but thinking it is jetting but not sure. I have to check the radiator for coolant tomorow. It was not smoking at all and the head gasket does not appear to be leaking at all from what I can tell.

Would running no packing be the problem or is it the jetting? I messed with the air screw and it did not fix it.

I may try putting a stock head gasket back in and see what happens.

The compression was checked and was around 160 to 180 when I did the cr head gasket mod. After the third time starting it my foot got kick backed up from all the compression so I do not think I lost compression.

Also since I did not have race gas at the time I am running 91 octane right now but am going to get some race gas tomorow. Could that be the case also?

Let me know your opinions on what I should try or what you think it is.

Thanks,
Jake

[crazedape]

Change the head gasket back to what you had it at. You messed up your squish when you did that. That should fix the problem.

[Aceman]

Don't run your silencer without packing, that's just silly. It's in there for a reason.

[deathman53]

you probably are running lean to start with. Also a cut down silencer will make alot of bottom end, very little top end. Silencers are the length for a reason and there is packing in the silencers for a reason.

[KFX400 RACER]

Yes I know the silencers come with packing but when you cut a fmf silencer shorter I can not get the packing to stay in. It jet plugs up the where the exhaust comes out. I still have the center tube in there to prevent that also but that does not help at all.

The reason I cut it down was that it helps lowend and I ride mx. Also I read in older posts that is the best way to run a fmf silencer. Also it was running just fine with no packing in there. They say packing helps with the exhaust pressure but I think it just makes it harder for the exhaust to come out. Some people ride with burnt out packing and never rebuild there silencers.

So should I change my cr head gasket with a stock one and would that help?

I think it could be my jetting but it ran fine with the pipe and silencer and the airbox cannot be much of a difference since it was already jettted with the stock airbox with the lid off and a kn.

That leaves with it being the head gasket.

I am going to try some race gas tomorrow and see why there is so much coolant is in the overflow bottle. If this stuff does not work then a stock head gasket is going back in.

Any other help will be greatly appreciated.

Thanks,
Jake

[Kirt13]

Looks like your going to do what you want......I would listen to what these guys are telling you. They are right.

[deathman53]

also I should add that k&n filters let alot of dirt in, if you choose to use them, make sure you put a prefilter on them. Your jetting should be a 160-165 main. Also with the cr gasket it could be too much compression for pump gas. I can tell you, I had a 86 250r, 80 over, pt type 6 pipe, stock carb, stock reeds, basically no lid(it had many holes drilled in the top), pt silencer, 165 main. Also a atc250r of mine: 38 a/s carb, v-force reeds, esr atc5 pipe, no lid, stock 40 over clyinder(ported), it had a 178 main in it(it had a lean needle). Now I have a 88 250r 310pv, cr ignition, cr reeds, 39 pwk, no lid, lrd pipe, it uses a 172 main and a atc250r of mine very simlar motor setup with the exception of a pt hi-rev instead of the lrd pipe and that bike uses a 170 main. I will maintain that you are running lean as the stock pipe is very restictive. I would change back to a stock or 85/86 atc250r head gasket. If you didn't know, one of the signs of running lean is that it runs very hot and tends to boil the coolant.
As for the silencer without packing, all it does is make more noise, your motor will run better with packing in the silencer. You should use a b8es spark plug or b9es instead of a br8es.
Please listen to us, I have 3 250r's(atc and trx) and will have another trx in another year. In total I have 7 bikes and do most if not all the work on them. I have friends that have 250r's also.
My friends 250r: 310pv, 38 a/s, lrd pipe, cr reeds, his wifes: ported 40 over, lrd pipe, 38 a/s, his other one: 300 resleave, 38 a/s lrd pipe, cr reeds. All of them run about a 165-175 main. Take out the plug and tell us the color of the electrode, we can tell you if it is running lean or rich.

[KFX400 RACER]

I am running a um airbox cover over my airbox. I have ran kn air filters for years on my quads and work on them myself also and have owned alot of quads and mx bikes. I have never had a problem with a kn sucking dirt. I also run kn air filter on all my muscle cars also and never had a problem. I am not fond of the foam filters at all really but I noticed everyone likes them better.

Well I got the plug out and looked at the electrode. It is mostly all black like it looks like it is fouled almost.

So if I am running lean and need to rejet what would be a close setting for me for the main jet size, pilot jet size, air screw. I live in IL for elevation differences. I do not know what I am running right now since I have not touch the carb on it since I have bought it other than rebuilding it. It does have different size jets than stock I know for sure but forgot to write down what they were. I have been wanting to get a 38 or 39 air stryker carb but not enough cash at the time.

Also I want to keep the cr gasket but would it be better to put a stock one in or a atc one? If I ran the stock gasket would I still have to rejet since the bike ran fine with the fmf pipe and silencer and did not stumble at all.

What is wrong with the plug I run and why should I run that plug?

I will have to figure out the muffler packing issue later once I get this thing running better since it looks like I have to buy another silencer since mine won't hold any.

Also were do I buy these jets at for my carb. What is the best place to get them from. Service Honda?

[atvmxr]

I know when my packing came out of my silencer, my piston melted within 2 laps. Makes it much leaner.....

[deathman53]

black means very rich, what size main do you have in the bike right now??? another thing you can do is to rasie the needle clip(it leans the midrange and part of the top end out). the reason for the different plug is that it burns the mixture better. I would put back in a stock or 85/86 atc250r head gakset(more compression), the cr gasket is too much for pump gas(most of the time). I woud get another silencer w/ good packing and do all of this at one time.

[fireburns99]

ok something isn't making sense. You raise the compression, change to an aftermarket pipe, silencer, and air filter, and now you're running rich???? :rolleyes: If thats the case it shouldn't have run at all before you did these mods. I'm comfused.

[KFX400 RACER]

Just like fireburns99 said but it sure did run fine for over a year and a half and I never touch the jetting. I did rebuild the carb when I first got it since the quad sat for two years but put whatever jets and settings back in the way they were.

Some of these guys saying I am running lean and now I am running rich.

I know you guys say to start changing stuff but I hate to work on it and change stuff and it does not help at all or is not the problem.

I am just getting confused on what is happening.

I am thinking of just throwing everything back to the way it was.

It ran perfectly fine when I had the pipe and silencer on it. though When I put the airbox on and change the compression this is when it started to run like crap coolant filled way up in the overflow tank.

I do not think it is the airbox since I had the stock one with no lid and a kn before I switch to the alluminum airbox.

Maybe it is cause I change the gasket.

Also I do not think it is the silencer running without packing since I had a dg silencer on it when I bought it and when I replaced it with fmf it had no packing. It ran fine like this.

So this leaves me to believe I need to change back to a stock head gasket.

[GT300]

What jetting are you running????

[Aceman]

You have too many variables since you last had it running right. Start eliminating variables by either fixing them or putting it back to the way it was. Pack your silencer, put your original head gasket back in, run the same octane fuel, etc. Guessing your problem when you've changed 4 different things all at the same time is the wrong way to go about it.

[KFX400 RACER]

Well I just got inside from changing the head gasket from the cr one to a stock one from cometic that I had. I think the head gasket was leaking alittle and that is why it was overheating alittle since the top of the cylinder surface between the gasket had some coolant on it.

But what of course all that work and that does not fix the problem.

The quad runs good till 1/4 and you can blip the throttle quickly and it runs fine also but when you go and try to go past 1/4 throttle and rip on the gas and hold it at full throttle it seems to be a bad miss. It also idles fine.

It has a new spark plug in it and has gobs of compression since it kicked my foot back once while starting it.

It sure sounds like a miss and so I checked all electrical connections on the bike and nothing made it go away.

Do you think it is the electrical system? It is getting spark since it runs but maybe not enough spark for high rpm.

Also thought about the cdi box might have went bad? Is that like a rev box?

So far I think it may be the electrical system on the bike or maybe the stock reeds on the bike are cracked or not working properly. The reeds where fine when I checked when I rebuilt the car when I bought the quad a year and a half ago.

Do you think it is the reeds?

Also I am running 92 octane gas so it should burn good.

Its starting to piss me off.

Anyone locals close to Monee, IL. that is 45 minutes south of Chicago willing to come out and help me or at least look at it?

[Kirt13]

Sounds like to me that you need a bigger main jet.

[KFX400 RACER]

Why the hell would I need a bigger main jet as tells me it is running way rich already and it does foul plugs once in a while so it is getting more than enough fuel.

If you say I need a bigger main jet I will get one I guess along with some other jets and try to rejet I guess since I have no clue what else to do other than spend more money on the bike till something makes it run better which I do not want to do but seems like that is all that is left.

So far people have been telling me its cause I am running lean first than say I am running rich.

Changing back to a stock gasket like you guys said did nothing except lower my compression ratio back to normal.

Tell me how more fuel to the motor would help it. All that would does is make it even more rich and foul my plugs out even faster. Would'nt that make to much fuel get to the motor and make my quad bog and run worse even more since it would get to much excess fuel to burn if I go with a bigger main jet?

I also stated that the plug color was black which is means its running rich and not lean.

But on two strokes it is harder to jet since it could be black from burning to much oil and not even gas in the mixture ratio so it couild be running lean but it just does not look like it.

It just does not seem like a jetting issue. The jetting could not be that far off from the parts that I took off and put on.

It is not a muffler packing issue since my dg muffler without packing ran just fine for over a year and a half on my quad and did not burn a hole through my piston like someone posted.

It also ran fine with the fmf pipe and silencer before I cut it and it was still with the stock air box with the lid off and a kn filter.

The new airbox I put on is run with no lid and a kn. The only change is it has no snorkel on it.

Also first time I rode the quad with everything that I did it ran pretty good and only miss at top end. It pulled hard through every gear and would pull the front end off the ground in the grass and then **** hit the fan.

[Kirt13]

I tell you what. Stop asking for our help. You keep getting upset and it sounds like you don't know what you are doing. Let some one work on it that knows what they are doing. You are going to destroy this motor. All of these things that you did to your motor and exhaust is painfull to hear. We are trying to help you not destroy this motor. Do what you want. Bottom line is, put everything back the way it was.

[deathman53]

put everything back how it was, see if it runs good. then put the airbox on(shouldn't make any change), then put fmf pipe on(full silencer also). See how it runs. I'm willing the bet that there is something with the fmf pipe and shortend silencer, maybe your jetting is way off. ALso what comes to mind is that, what are you premixing your fuel too???? I have heard that too much oil will foul plugs and cause symtoms like you are describing, another thing, are you over oiling the airfiter? Did you ever raise the needle clip also, that will lean your mix on top end, you haven't got back to us on what your main jet is right now either. Defenetly keep the stock head gasket and torque it proerly to 22lb's in a Cris-cross patern. There is something going on, but the only way to find it out is to change one thing at a time. Please stop being so pig-headed listen to us, But first provide the following information, main jet, needle, idle jet, oil/gas misture, have you check your spark also? it could be a weak spark, blue spark is weak. We want to help you, but you have to listen to us.

Did you do a leak down test also, overheating can be a air leak? I had a esr330 on my atc250r, it was running rdiculasly rich jets, 190-210, when I took it off to put a stock cylinder back on, I found a small crack in the carb-head air boot, that is what caused it to run so hot.

[86 Quad R]

if ya want to run the cr gasket then i would suggest that you clean all surfaces WELL and use a sealant on both sides of the gasket. some use gasket sealant but, i have had great luck with fast dry krylon paint(on both sides of the gasket, allowing to dry).

check the float level on the carb, re install the carb with the jetting you have and set the plug gap to .018 - .022" and do a plug chop and jet it according.

[beerock]

You know sometimes all you guys make people in need of help run in circles doing this and that, telling people to take apart there motors, put it back how it was etc.

its OBVIOUS its LEAN any motor that cuts out like that means its starving for fuel. go up 3 stages on the main jet and lower the clip on the needle1 notch from center

now please tell me im wrong too ;)

that was retarded cutting the silencer R's are made to scream not for bottom end, even the big bores...