And then there were two.. 1976 GT250 Rebuild

[Hurco550]

Hah! parts sharing is something that is lacking (openly) we have a sell thread, but maybe an ask offer thread is in order as well.

Great idea man!

 

[Hurco550]

New air filter made from uni foam and oiled up and the new boot on. Cleaned up the air box and put it on. For all intents and purposes she is "done", but I am still having jetting issues...

Won't run off of the pilots without choke. (I've tried 20's and 25's). The mains are 92.5's, which is stock lashup. Gotta order in some new jets. Any ideas where to start? 900ft. Above sea level I believe. Dies without choke. Help?

 

[teazer]

Are you 110% sure that the carbs are really, really, really clean?

There are a couple of tiny little holes that the air/fuel mix sprays out of at idle and they are usually plugged or partially plugged. Technically they are the pilot outlet and the bypass but who's counting?

 

[Hurco550]

Are you 110% sure that the carbs are really, really, really clean?

There are a couple of tiny little holes that the air/fuel mix sprays out of at idle and they are usually plugged or partially plugged. Technically they are the pilot outlet and the bypass but who's counting?

I would have to say I'm 109% sure. Completely disabled, ultrasonic cleaned, soda blasted (I know that does nothing to clean passages) then multiple cleanings with carb cleaner spray/ compressed air through all passages. Same treatment with all the brass minus the soda. I didn't use the rebuild kit brass as the Jets were way of factory specs (112 mains I think) as opposed to 92.5.

 

[Hurco550]

Plus, new filters in line from the petcock

 

[Tune-A-Fish]

Hold the drain tubes up and verify the bowls are in fact full when running, sounds like starvation to me??

 

[Hurco550]

Hold the drain tubes up and verify the bowls are in fact full when running, sounds like starvation to me??

ill give that a try tune. I just feel that its pilots (not arguing, just saying my guess) because when it gets past pilots it seems to run fine. Does that still sound like starvation?

Im going to go ahead and order a few different jets. My book calls for 92.5 mains. Another book calls for 95 main left and 97.5 main right. I don't know why there would be a difference side to side? I know some sleds call for different mains left to right depending on slight variations of intake boot length ect... but mine are the same. Anyhow, I guess ill just go a few sizes each way and start doing plug chops...

 

[Tune-A-Fish]

Oh hell no I was thinking you were falling off after idle... nvrmnd

 

[Tune-A-Fish]

Pilots need to be closer to 27-30 and seriously would go 28-30 to start I just went and looked through my notes on the 550 and had the same issue and increased 5 sizes over stock before getting a good 1100 idle then did chops to dial mains.

 

[Hurco550]

Pilots need to be closer to 27-30 and seriously would go 28-30 to start I just went and looked through my notes on the 550 and had the same issue and increased 5 sizes over stock before getting a good 1100 idle then did chops to dial mains.

good deal. thanks man. you happen to know your elevation? Ill grab some pilots and some rich mains and chop it down. It wouldn't be so bad if that dang air box wasn't such a pita to get on and off..... lol

 

[Tune-A-Fish]

good deal. thanks man. you happen to know your elevation? Ill grab some pilots and some rich mains and chop it down. It wouldn't be so bad if that dang air box wasn't such a pita to get on and off..... lol

350 feet so im good on oxy, but that really is a non issue unless super high when it comes to idle

 

[Hurco550]

google says im 981 here, but im taking the bike down to Hendersonville nc for meltdown... its 2150 lol dang...

 

[Tune-A-Fish]

google says im 981 here, but im taking the bike down to Hendersonville nc for meltdown... its 2150 lol dang...

Yeah it will be okay, bring a set of plugs but doubt you will foul out

 

[irk miller]

E has a plug cleaner. It'll get you through.

 

[Hurco550]

Yeah it will be okay, bring a set of plugs but doubt you will foul out

hahaha ive ridden enough two stroke sleds that I never leave the yard without plugs =) =) rather be rich than lean though eh?

 

[Tune-A-Fish]

Detonation is best left to the pyros

 

[teazer]

When you pull the carbs to fit new pilot jets, please take a moment to be 111% sure that the pilot jet outlets are clear and flowing the same on both sides.

 

[Hurco550]

When you pull the carbs to fit new pilot jets, please take a moment to be 111% sure that the pilot jet outlets are clear and flowing the same on both sides.

Absolutely will man. When the two stroke guru gives you advice, you take the advice!!
Thanks Teazer

 

[teazer]

Absolutely will man. When the two stroke guru gives you advice, you take the advice!!
Thanks Teazer

I'm no guru. Just passing on what I found on carbs over the years. I had a set yesterday from a 750 that looked clean and after they were fully cleaned, when I tried to blast I found that the flow through those tiny passages were very different from one to another. The other PIA on many mikuni carbs is the tiny starter jet which lives at the bottom of a deep hole in the bowl and like all trolls, it loves to cause trouble.

I use a can of carb cleaner to spray through each drilling and I compare one carb to its partner to see what the flow of spray looks like. Do it in a well ventilated area of course.

No guarantee that's the problem, but it is worth checking if the carbs are off anyway. ;-)

 

[Hurco550]

I will definitely check em out when I have them out again. Like you said, I might as well when thet are out. Sure wish they made the dang air box easier to get in and out... makes me understand why people run pods lol that's not what im going to do, just saying I understand. Ive read where people replace the air box with a large single uni filter but still keep the two into one collector before the carbs. Ive never heard any actual results from the mod whether it is beneficial beyond the ease of removal of the carbs..