Trying to tune a new Full Spec 49. I have the high speed nearly closed (1/4 turn from closed) and have worked the low speed from 3/4 turn to 2 1/2 and cannot get the bottom end to clean up. I can get the middle and top to be nice and crisp when I set the low speed at 1 1/2 and top at 1 1/4, but the bottom is real rough and sputtery no matter where I set the low speed adjustment. I almost have to roll the throttle open easily until mid lever throw and then get on it for maximum performance. Any ideas? Engine is ported/epoxied/trued compression is 185 with fresh gaskets, fuel line and filters.
carb tune quandry
- Thread starter Pablo
- Start date
Yes. Call Ed and get his recommendation.
I've tried tuning his carbs by myself and kept chasing my tail for two weeks.
Then I broke down and called him. After listening to him for a half hour :biggrin:, I got his recommendations for jetting the carbs both in single and dual config.
His specs were dead-on.
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
I am having the same issue with my 44's. mid to top is fine. Bottom is ick. 1 turn out on the low and if I go 1/8 turn either direction is gets worse. But the bottom is not clean. Problem = Popoff is not right. Gonna try and get some time this weekend and play with it.
- Location
- South Florida
He already talked to Ed. Did you get the jets in that he recommended and it still won't clean up?
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
Mine are not Full Spec. Just a similar carb issue.
- Location
- South Florida
Carb issues SUCK!
#ZERO
Beach Bum
- Location
- Florida - U.S.A.
Maybe your ignition advance might be the problem.
What type of ignition are you running and what are your jetting specs?
What type of ignition are you running and what are your jetting specs?
Listen to the exhaust note when you are just planed out, that is the pilot jet. Then slowly open the throttle and listen at the piont where the pipe surges, thats mostly the popoff. The engine should be sputtering some for best throttle response. Its is very easy to clean up the low side by raising the popoff and dropping the pilot, you will know it has been overdone when then its cold natured and tends to hesitate as the throttle is opened. Big carbs usually need to be very rich for good response.
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no new jets. thought i'd troll the X b4 i go screwing with it more...to be continued.
Agreed that carb issues are the worst! There are 3 of us riding this thing and I think we're all stumped. It's got a b pipe, total loss ignition, 9/15 hooker, and feels more like it's got a stock ignition with stock impeller. It doesn't feel like an air leak or cavitation or anything like that. When I rode it last, it had smooth acceleration but semi-slow acceleration compared to what it should be.
I don't want to trash the thread up but the only two things that are unknowns to me are the porting and the single carb on a 62T case. Maybe the dude that built your engine raised the exhaust ports a good bit and it ruined the bottom end performance.
I don't want to trash the thread up but the only two things that are unknowns to me are the porting and the single carb on a 62T case. Maybe the dude that built your engine raised the exhaust ports a good bit and it ruined the bottom end performance.
Go easy on the engine builder bashing. He's been fine and has a good rep here on the X. I'm sure it's a simple carb issue...just nailing the jetting along with fine tune of low and high speed screws. I've got a ATP billet carb mani that's throwing off the combination. I'm waiting on bigger pilot jets 140 or 145 to install. Got 137.5 in now. Word is that the mani is allowing too much air. Don't know if it's air velocity or volume, but going up in pilot jet is the recommended trick now. Just thought I'd see what some of you recommended as well.
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More importanty, what are your pump specs?
- Location
- South Florida
I know who your builder was and won't name or bash him if you're not wanting to but.....
the package deal should have been TESTED and ready to go when you got it. This has cost you 3/4ths of the summer. Doesn't seem right. That's all I will say.
the package deal should have been TESTED and ready to go when you got it. This has cost you 3/4ths of the summer. Doesn't seem right. That's all I will say.
SUPERTUNE
Race Gas Rules
- Location
- Clearwater Fl.
You need to use big low jets so your going in the right direction there, also set the high speed screw at 7/8 turn and change high jet until your very close, then you will have a 1/4 turn either way adjustment
Sweet weekend tuning rather than riding. Man it's great. I tried lowering the popoff today with a 80 gram spring from a 115 (thx mcdog). It made the whole thing worse. Needle and seat was a 2.5. Was thinking that N/S was quite a bit smaller (more like 1.8) so I was going to go up to a 2.0. Since the 2.5 was crap with the 80 spring I went down to the 2.0 and used the 115 spring. It feels better, but still will not fully clean up on the bottom. I haven't tried the 80 spring with the 2.0. What's a better move:
1. Go lower on spring/popoff
2. Larger pilot?
I've got a 137.5 pilot in now and have 140 and larger on the way.
1. Go lower on spring/popoff
2. Larger pilot?
I've got a 137.5 pilot in now and have 140 and larger on the way.
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