Engin Cuts out on top end

[clutch22]

My R cuts out when it gets in the upper rpm's ... is this my reeds? or what?

[honda380]

sounds like a jetting problem to me. if it sputters and spits, then it is most likely jetting, if it dies then its probably going to be an expensive fix... post the symptoms, youll get more help that way. Corey

[clutch22]

Yeah... it kinda sputters and spits....

It wouldnt have anything to do with me putting a 11tooth sprocket on, would it?

[RichM1983]

Its probably the main jet. I had one that was to rich and it did the exact same thing. I changed the jet and it runs really great.

[Scott-300ex]

Yeh man go up on your main jet.

11 tooth, Damn dude, thats low. :eek:

[parttime]

is this something that just started or ongoing?has there been a serious change in temp?if not, check stator seen alot of r's do the same thing becuse of a stator and even seen a couple with a bad crank seal do the same thing.

[clutch22]

When i got my R, the guy didnt give me his jets that he had for it... i dont know why... he was gettin out of riding quads... So if i cant buy those from him, I'm supposed to buy jets made for my model Keihin Carb, and not buy them for a 250R , right?


If anyone has a kit they wanna sell, lemme know. But I need to fix this problem fairly quick... Gotta dune trip planned for spring Break.

[RichM1983]

You should be able to go to a honda dealer and get the jets for the keihin carb. I do believe that not matter what keihin you have they all use the same jets just different sizes. I was able to get mine from the honda dealer and they were in stock.

[clutch22]

Sweet... I'll call them tommorrow...

[86 Quad R]

what plug gap are you running?

[clutch22]

Originally posted by 86 Quad R
what plug gap are you running?

i dont know... i've never messed with that... i just put it in and go.

[86 Quad R]

close the gap to at least .022 and give it a whirl ;)


edit: stick in a fresh plug gapped to .022 and do a WOT plug chop and see what color the plug is.

[LT250Racer609]

i highly doubt its the plug gap...because 99% of the time when i put a new plug in, its exactly how it is out of the box andi have NEVER had a problem with the gapping it came with...what plug tho?? BR9ES is what you normally run, BR8ES is a little hotter...

its your jetting or what are you mixing your gas ratio at?? you might be mixing it a little too rich with oil and its burning up the gas all nice and fast but can burn up the oil fast enough...this would choke out your spark and give you a sputter.

do you know what size bore you have?? MM carb? what pipe are you running?? stock reeds?? let me know this i can help you. Also check what size main jet you have in there, its very easy to do...

If you look on the bottom of your carb you will notice theres a big plug like screw on the bottom of the bowl. Turn your gas off and loosen up the 2 clamps on each side of the carb and just rotate your carb so you can see the bottom of the bowl perfect...now take that plug off. You will see your main jet sitting there once you take that off. I believe its a 6mm 1/4" socket that you will need but unscrew your main jet...when you get it out, there will be a number on the side of the main jet....come back and let us know what that number is along with the following mods i asked you for.

[fireburns99]

Originally posted by LT250Racer609
i highly doubt its the plug gap...because 99% of the time when i put a new plug in, its exactly how it is out of the box andi have NEVER had a problem with the gapping it came with...what plug tho?? BR9ES is what you normally run, BR8ES is a little hotter...

I disagree... The stock ignition system is weak on the R's. If the compression has been raised, then spark may not be strong enough to jump the gap. On my R i run a BR8es and i have to gap it at .018. If not it sputters and is weak on the top end.

[LT250Racer609]

i dunno i have never had a plug gap problem on my one motor with the 310 that had over 245psi of compression (had stock electrical system) and in my motor right now i do have a full aftermarket electrical system and have never had a problem then either....i dunno maybe, but i doubt that this is his case.

[fireburns99]

Originally posted by LT250Racer609
i dunno i have never had a plug gap problem on my one motor with the 310 that had over 245psi of compression (had stock electrical system) and in my motor right now i do have a full aftermarket electrical system and have never had a problem then either....i dunno maybe, but i doubt that this is his case.

I agree it sounds like jetting to me too, but i was jsut stating don't rule out a weak spark. And its not a problem for everyone, but for some.

[Eddiesanders250]

Do a plug chop and check the color......

Let us know the color, you want it to be the color of a brown paper bag..

[clutch22]

ok ... i've got a 200 main jet ...
paul turner pipe, 2nd bore with long rod kit.... Boyesen reeds

[LT250Racer609]

your main jet is huge...put in a 170 and try that...200 is huge. Im assuming you have a 38mm carb??? hell, i had a 200 main jet in mine with the 310 and it ran perfect....

[clutch22]

yes i have a 38mm carb....
So does everyone else agree that i should start with a 170.... and buy some sizes around that?

[fireburns99]

Yea man 200 is HUGE!!... I have a really ported stock cylinder and run around a 185. So yea i would start at a 170 and see.

[LT250Racer609]

ok i will tell you my set up...

I have a LRD pipe, Boyseen Rad valve, 38mm airstryker carb. and a ported and polished GT thunder 265 cylinder on. Right now i have a 182 main jet in and its running perfectly brown like it should, but infact i most likely could get away with a 185. When i had my 310 on, i had the 200 in and that also ran perfect but prolly could have gotten a little more out of it like a 210. A 200 main jet on your setup is just over kill. Try a 170-175 and read the plug. If its a little lean jump up a few sizes....just go to a shop and get like 4 different size main jets. Most likely your gonna end up prolly in the high 170's.

[atvmxr]

I doubt he knows what kind of carb is on there. I run a 158 main or so on mine...... but with this "cold"air 55-60 its starting to fart on the top of 5th and 6th so Im going to jet up a little this weekend and see if it helps, maybe just need a new plug. Its probably a year old.



i heard somewhere that smaller bores COULD require a bigger jet because the smaller displacement decreases the velocity and thus the "pull" on the fuel and a larger jet is needed to get proper flow.....

neil or someone, what you think about that?

[clutch22]

I got some jets today... put the 170 in... Runs great now... thanks guys

[LT250Racer609]

Make sure to check your Plug!! if theres any white ring on the center electrode it too lean...you wanna have it brown.

[XANDADA]

An easy check is the reeds, a cracked petal will cut out on top.

[clutch22]

Originally posted by XANDADA
An easy check is the reeds, a cracked petal will cut out on top.

Ya.. my reeds are usable.. not great... so when i bought my jets today, i ordered some reeds.