I have an 86 250R w/ an FMF Gold series Fatty pipe/sil., K&N filter (just cleaned and lubbed) and V-force Reed valve. The thing should have some power over stock? wrong!

I run a stock carb w/ 155 main, #6 needle in the 3rd clip position and I believe it has the stock pilot (48 but I'm not sure 'cause I've never checked) and I run 32:1 w/ Klotz technoplate.

Now, she lacks lowend. Not only that but sounds unclean and has a sputter ALL THOUGHOUT LOWEND IN FIRST GEAR. But it sounds fine once I shift into second. Now THAT"S weird and makes no sense to me. It hits kinda hard when it finally does come on and seems to rev out ok but will actually flatten out when shifting from 5th to 6th at full throttle. The intake where the reed valve is is missing a bolt but that should be a problem should it?? afterall it is still sealed by the other bolts and a gasket.

The main problem is the holeshot. My brother's stock 86 R beats out consistently beats it out off the mark by 2-3 quad lengths and then as I hit the midrange it doesn't really catch up it just stops the stock R from pulling away.

What could be wrong??

 

You should do a plug check at 1/2 throttle to determine proper needle height, and a plug check at full throttle to determine the proper main jet.

Did you re-jet after putting on the aftermarket parts?
You should have had to go up on the main jet AND drop the clip a position to start out with.

Yes! Replace the missing bolt! It can cause you to run lean, and possibly ruin the engine!

 

have you ever over oiled filter? i have. it doesnt run to good. not saying you did this.

 

Have you been riding this machine all "winter"? I don't know where you live. If you left it sit over the winter with fuel in it, your carb is likely gunked up, and stale fuel will make it run for sh*t also. Any YES you want to replace that bolt, you run the risk of leaning the motor out and burning it down. How long have you had this machine for? A motor that needs a top end, or is jetted incorrectly, or has a gummed up carb, or has old gas, can easily get eaten by a stock machine in good tune with good fuel.

 

OK. to answer all questions:

I bought the machine over the winter and didn't add the aftermarket stuff.

I put the 155 main that it came with back in after getting bad results w/ a 160 and 158.

I dropped the clip from 4th (which is how I got it) back to the stock 3rd postion and it doesn't run any better. Maybe i should drop it to the second clip.

I've done many plug checks at full throttle and the insulator is always brownish tan. the main is fine.

I've haven't done a half throttle plug check yet. Maybe that'll fix it.

I've drained the tank and cleaned the carb w/ carb cleaner twice.

If the topend needs a rebuild, I wouldn't know 'cuz i've havent't come to that point yet.

The filter was just cleaned and oiled about 6 weeks ago (it's a K&N so it should still be OK)

I'll try a closer inspection during a plug check to see if the color varies from the electrode down to the base of the insulator. How does that work again?? If the top of the electrode is, say a bit darker and the insulator from top to bottom goes dark to tan, does it mean that my needle is rich or that the main jet is rich?

No one ever addresses the pilot. I'm assuming the pilot is still a stock 48. Could that be too lean?? What you all done with your pilots after putting on pipes?

 

Being that you bought the machine recently, I'd do a compression check before I went jetting crazy. Go get a comp check gauge and check your compression. Warm the bike up with a decent ride, put the comp checker in the spark plug hole, hold the throttle wide open, and kick it over vigorously for 5-10 times. Let us know what the PSI is, and we'll know if you have to go in the motor. If your motor is properly tuned with good gas and the aftermarket goodies, and the top end is in good shape and your weights are comperable and you both have stock gearing and tire sizes and you both are of equal skill, you should pull away. The mods you listed are a good startig pint for a machine that will tearas*. Since you've alread got all the basics, a good porting job and a bigger carb while you're doing your top end rebuild will make your machine scream. I know a shop run by a former honda tuner that will port you for whatever powerband you want and will do it for a very reasonable price, he has nothing but praise from anyone I know to have work done by him. But you want to make sure you have a good seal on the intake, so replace that bolt. It's a lot cheaper than a leak down tester or a seized motor.

 

psst. up your pilot jet.

 

Some things to double check.
1) Make sure bike is at operating temp when doing a plug check.

2) Use a BRAND NEW plug! It must be white when you install it, or you WON'T get an accurate plug reading (I know, I almost wasted an engine quite a while back by trying to use a used plug)[img]i/expressions/face-icon-small-shocked.gif[/img] The plug looked fine because it was dark from breaking in the engine, but when I installed a new plug it was WHITE for the next 4 jet sizes up!!

3) I belive the motor is supposed to be COLD when you do a compression check, not warmed up.

4) Unless you have a certified small bore compression tester, there is NO TELLING what reading you are going to get! There can be more than 50lbs psi difference in readings between different automotive gauges. I know, cause I've seen it myself, and my engine builder PROVED it to me on the spot with my friends own compression tester! The best thing an automotive compression tester is good for, is simply telling if you have a difference in compression from what you started with (using the same tester).

Oh yeah, I believe the stock setting on the clip position for the 86'R, is on the 4th position, so raising the clip is probably causing the problem to get worse! Try dropping it all of the way to the 5th position, and see if that helps.

Like Dill said, you MAY have to up the pilot jet, but the 1st thing to do is replace that missing bolt! You are just p$$ing in the wind until you know you don't have an air leak, and are pulling in excess air there.

 

Wait a second 2fun. How are counting clip positions? I am counting from bottom to top meaning to me , the 5th position is the uppermost one. When I opened my carb it was at 2nd one from the top. Now it's in the 3rd position (in the middle).

So explain again, where exactly are saying my clip should be? the bottom-most clip?

 

Always count from top to bottom.
Top notch = position #1. bottom = 5th
Do you have a manual?

You drop the clip to raise the needle, thereby richening the mixture.

A lot of this is explained in the manual.
Kinda confusing I know. [img]i/expressions/face-icon-small-wink.gif[/img]