last week when i put mine together like i said in the other post i didnt use a base gasket, just yamaha bond, lowering the compresion. they both run good, until we let off the throttle goin down hill or about 1/4 throttle there a little ping, i just went to the dealer to pick up a boot and talked to them, since its not just the head thats been lowered the port timing is off, they said i should retard the timing? i was thinking at first to advance it until i read some more about it. so should i retard it or just put the base gaskets on? before i put mine on i opened the intake port some, knife edged the bridge, opened the boost port and cleaned the pickup ports on the bottom, i didnt enlarge the intake windows or exhaust.
timing
- Thread starter Reaper26
- Start date
Did you plug chop to confirm jetting?
I would be looking at re setting the idle and lifting the needle one clip richer.
Then plug chop at 1/4 to 1/2 throttle if the pinging goes away.
It may just be it is a little on the lean side.
I would be looking at re setting the idle and lifting the needle one clip richer.
Then plug chop at 1/4 to 1/2 throttle if the pinging goes away.
It may just be it is a little on the lean side.
Try upping the octane rating of the fuel some, it may just solve the problem, if it does not put the base gasket on.
Upping the octane rating may just help, if not put the base gasket back on.
http://www.dragonfly75.com/motorbike/timingcurves.html
A bit of info on timing for you.
What is the compression?
I may be barking up the wrong tree and fitting the base gasket will possibly cure your problem, but pinging at 1/4 throttle and on overrun talks lean mixture or low octane to me.
A bit of info on timing for you.
What is the compression?
I may be barking up the wrong tree and fitting the base gasket will possibly cure your problem, but pinging at 1/4 throttle and on overrun talks lean mixture or low octane to me.
What is rest of set-up?
Low octain or excessive timing would show most at WFO under heavy load. AS Blaaster mentioned try richening needle, and/or fuel air screw.
Did you change anything from previous set-up other than no base gasket? Your porting mods new?
Low octain or excessive timing would show most at WFO under heavy load. AS Blaaster mentioned try richening needle, and/or fuel air screw.
Did you change anything from previous set-up other than no base gasket? Your porting mods new?
ok ive got it at work with me, im about to tear it apart, the plug now is a little wet and black and compression is low-130. Larry, i have boyesen carbon fiber reeds, reed spacer, stock pipe, im going to go ahead and take the cylinder off. when i put it together this time i changed my main jet from a 250 back to 230, needle is on 3, air screw 1 1/4 out. my altitude is 712 above.
130 on compression is not low
needle in the middle clip.
stock pipes, air filter and air lid on?
needle in the middle clip.
stock pipes, air filter and air lid on?
130 compression is fine.
Float level or crap in the needle and seat will cause a wet pipe.
The main jet should not have any relation to fuel in the crankcase as it only sees service at above 3/4 throttle and will not cause flooding.
That Dyno jet needle should be in the trash can, the taper is possibly not correct , this may be the reason for the Ping at 1/4 throttle.
The correct needle to use for your mods is the stock needle on the middle clip.
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Im no guru but, running no base gasket is yes going to raise the compression but also retard port timing, which raising compression isgood but retarding port timing is bad, you really would want to run thick base gasket which will simulate a slightly advanced port timing which will yield more power, then have head milled an chambered accordingly to achieve desired compression. Or just have cylinder properly ported and run normal thin paper base gasket. Old school performance was to run 2 base gaskets an mill head
Another "old school" trick is "notching" the piston to adjust port timing, simular to a Vito's superstock piston. Though not quite as good as actually raising a port because you don't get the same time/area values. It would be useful for expeimentation especilly if you plan on doing some porting and piston replacement in the future. Tho a butt dyno isn't accurate it is as far as "driveability" because once you take it out of the cyl you can't put it back.
Have to remember, a little is alot when it comes to timing, 1mm might be 10* timing. This is where a degree wheel or port mapping program is handy.
i put the base gasket back on, runs good, smokes ALOT im not sure if its cuz the pipes and packing are soaked, but i filled my tranny oil up before i left work yesterday i rode about 15 mins, stopped smoking as much after it got good and hot, then i just happened to check the sight glass and the oil was at the bottom. so the oil could be leaking under the crank from the tranny, just figured the leak test would have showed that, i took oil cap off when i did it, and it held 5lbs for 30 mins then i unhooked it and put it back together, im guna fill it up again and keep a close eye on it to see if thats what it is, im also going to change the silencer so i know its not that making it smoke so bad. i also put the 250 jet back in and re adjusted float. the ping is gone, just gota make sure im not loosing my oil.
With the K&N filter and the lid off it might pay to go up to a #260 main and plug chop before you ride much more.
If you are loosing tranny oil, leak test now to make sure it is air tight.
What oil are you using?
If you are loosing tranny oil, leak test now to make sure it is air tight.
What oil are you using?
