'82 XJ650J will only run on choke some times

I was given this bike as a project bike to keep me busy by a generous friend. I have been resto-modding it for the past 11 months.

Nearly getting to the end with the carbs in after I have completely overhauled them; new correct jets and needles, throttle shaft seals and shims(from Len), cleaned and super light polished every everything inside, the needle/diaphram clunks down smoothly and rises when gentle air is blown through the body. I also replaces the engine to carb intake boots with gaskets and I'm using the stock style paper air filter

Now the issue is, the bike with start hard and fast only when the choke is full on and any roll of the throttle will cause it to bog down and die. When it does run on choke, there are little pops intermittently on the intake side of the engine. I have the idle screw out about 3 turns. I have check spark on all cylinders and when she is running on choke all exhaust pipes are hot. I have checked valve clearances and all are good on intake and exhaust sides. I am using an auxiliary gas tank so I can do the carb sync and colortune, so I plugged #3 intake port. The engine had a complete top end rebuild. The carbs were dry set to 17.5mm and wet set to 3mm. The carb rebuild kit came with crappy rubber gaskets and I did obtain the proper fiber gaskets for free float movement.

I can't think of anything else, but would like some ideas on what my next best steps would be to get the engine to run on the carbs right so I can sync, colortune, and start riding again.

I will post my project in another post in the forum.

 

Where was that kit from and what did it contain? Normally, it is best to stick with the original brass Yamaha carb parts unless they are visibly damaged - excepting the float needle valve, which usually comes as a set

Make sure the bowls are filling all the way using the clear tube method, sometimes with external tank with filter they fuel doesn't flow well

And it looks like you were very thorough but I don't see a bench sync, was that done?

 

The kit was from Amazon and had all the parts. The carbs had larger jets installed, not the originals, from 2 owners before, they had straight cut-off pipes and the intakes on the valve head were all coked up. What was installed were 210 for the main jet and 60 for the pilot jet, I installed from the kit Main jet is 112 and the pilot jet is 42. The exhaust silencers I installed are very close to the originals, EMGO slash-cut retros with a lot baffling and the exit hole is a bit restrictive, overall very quiet. The needle and emulsion tube were used from the kit because the original emulsion tubes were corroded. I still retained all the parts left over from rebuilding the carbs

I checked the fuel levels with the same source, using the auxiliary tank and filter when I did the wet set, and the bowls filled with no issue. They also filled fast and flowed pretty darn fast when I tested the flow when draining the carb directly back into a gas can.

I did do a bench sync, sorry about not mentioning that. I tried to be through as possible to explain all that I did up to this point.

 

Carb holders tightened up enough? Sounds like vac leak, I just went through this on my Seca. My son and I worked on it together, had him install the carbs and tighten them up. He misunderstood "not too tight" as barely tightened at all LOL. Had a hell of a time tuning it until I checked those clamps

 

Confirm the vacuum plungers move freely - I also used the needles and emulsion tubes from a kit which turned out to be the wrong size and bound up so tight the plungers wouldn't move. Same symptoms, if I turned the throttle slowly rpms would rise to a point then the machine would die.

 

What brand? Not all of the kits out there have all of the correct parts.

 

actually wrong rebuild kit, got it from ebay

https://www.ebay.com/itm/385318948349

 

Contact Chacal and her will get the correct kit/parts for you. I also would use any orignial parts unless they have been tampered with.

 

UPDATE.....I did get another kit, had different parts. Different needles, jets that are stock numbers, new floats and solid metal float needles. Sealed up the intake boots from the carbs to the cylinders with hi-heat silicone. She now starts up, a bit rough the beginning till she warms up. The throttle rolls and responds very nicely. No lean popping, I set the idle mixture out by 3 turns for now. Next on the agenda, sync, colortune and start riding. Thank you all for your advice