1200 into a 1000 chopped

[ekvh]

I put the pump back on mine, and no change discernible by me. I'm sticking with the 77's this year. Next year, this winter, I may try the Magna carbs again. They look to be easier to jet if on the outside.

 

[ekvh]

Had a chance to try something different, but I'm starting to think Joe Drum is right: the fuel isn't keeping up. It could still be that I need a bigger main. Right now I'm at 140 main, 70 primary, coupled with 140 and 70 air jets in 77 764A carbs. Today's test was two washers under the slide needle. I might go try stock air jets again, and if no change, try a 150 main. The deal is when I hold the rpm at say 8k, it will go, bog and then go again. If it was too much fuel, I think it would stay bogged, but it surges, then bogs down. Plugs look better with the extra washer, but every bit of fuel going though that needle hole is through the main, so I think it's still to small. Love to here anyone else's opines about this.

 

[dan filipi]

How does it do at lower than 8k rpm?
Could be your fuel pump isn't keeping up at that rpm?
Jetting up will affect everything off idle.
If your plugs are looking good then I'd say the jetting is fine.
You might be at the point here you'll have to see what the air fuel mixture looks like to get this right.
Too lean at those high rpms could be bad.
Might be worth one of those spark tune things to see what's going on.

 

[joedrum]

yep as of this moment im getting blistering revvs ....out of hooch I just got the grip throttle hooked up started right up .....I don't think hooch has eber ran this well .... im convinced the the motors are maxing out the carbs in everyway possible ....it was clear to me that the stoch rack would not work on this motor ... or be moded to work ... why im here today with a single set up ....wont be long ill be test riding it ...whew long battle

 

[ekvh]

Okay, I just went 65 primary, 160 main, no washers. It screams to 8k then sputters. Could the spark gap be causing this?

 

[joedrum]

out of gas .... LOL

 

[dan filipi]

Sounds like a rev limiter. :mrgreen:

I lost track on this, what ignition are you running?

 

[ekvh]

77 with Dynalll. Gl1500 coils.

 

[backlander]

I have a question eric, what kind of cfm are the 764's flowing? Could it be possible that your carbs are not big enough to handle the job and your running out of needed flow at the higher rpm. According to my cfm calculator, a 1200cc mildly modified engine would require approx. 158 cfm to run at 92% volumetric efficiency. The problem is, I can't find the specs for the 764's to see if they can supply that

 

[mcgovern61]

joedrum » Fri Aug 30, 2013 1:06 pm[/url]":vhsgkb2i]
out of gas .... LOL

:smilie_happy: :hihihi: :ahem:

 

[ekvh]

I've never found data on cfm for Gl's. I was thinking it would keep up because the cams are the same as the 1000. The 78 and up Gl's all went with smaller Venturi bores, so you now have the whole speed vs volume of filling thing. I expected this to be similar in power band to the 77 gl1000 because of the cams. I just put the stock air jets in and no change, maybe worse. I'm pretty frustrated. I need to cool off and figure out how I'm going to explain to the wife that I worked on the bike again all day. Maybe tomorrow I'll try a washer under the needle again. Currently I am at a 65 primary main , 160 secondary main, 60 and 120 air jets, no washer under the needle. I'm wondering if it's an ignition problem. 160 is a pretty big jet for these bikes.

 

[ekvh]

Advice from elsewhere, and partly based on Dan's observations riding Joe's bike, I went back to stock, almost. I think I started the jetting changes based on some backfiring which I later found to be from a leaky float valve. I should have gone back to stock after that. This morning I went stock except a 70 primary and two washers under the needle. It was better and pulled up to 8500. I think I'll go back to one washer. If I jet up again I won't jump as much. Going for a ride now and check plug color.

 

[joedrum]

cool

 

[Ansimp]

ekvh » Sun Sep 01, 2013 4:40 am[/url]":2jwr9k5r]
It was better and pulled up to 8500. I think I'll go back to one washer. If I jet up again I won't jump as much. Going for a ride now and check plug color.

And I was feeling bad about pulling over 7000 on the Rats Nest :moped:

 

[joedrum]

well im glad my battle with hooch is over

 

[ekvh]

65 degrees this morning. Decided to go to one washer under the needle. Result: pulls linearly to 10k. I never took my 1000 that high, but it was like silk all the way. I don't plan on doing that often. So lesson learned, basic science rule #1: only change one variable at a time. In this case I kept changing variables, but got taken by a leaky float and slide springs that were too weak.

When I switched the springs, I should have gone back to pure stock settings. Currently it is stock, except one washer under the needle, and a slightly larger 70 primary jet instead of 62.

 

[backlander]

That's great eric, glad you got it all sorted out.

 

[ekvh]

Just went out for an hour. It is about there now.

 

[joedrum]

yep sounds cool ...I went for ride today its hot here today but the early ride was allright ... hooch did greart also ... nice to know you getting stock carbs to work .... they gave me fits and I wasn't jumping in cures .....in my case I was running out the bowls of gas ... today im finding the with a handful potencal has a price ... mpg ....hooch pushed me and my daughter around like a an empty freaight train ...

 

[slabghost]

Where did you get the 70 primary jets? How thick are the needle washers?