Jet recommendations / carb work

[Donut 77]

Thanks Chris

[fabiostar]

Getting there indeed! Although I I didn’t think I’d have to sort all this out on a bike that was sold as running perfectly, I do love working on bikes and I’m always learning a lot so I’m not complaining!
I got the carb boots on EBay, £33 for the pair

just a we note. you have the front pilot screw and rear the wrong way round. . my old crusty memory says you want the rear one slightly richer then the front, no big deal running wise but the rear runs a tad hotter.

Thanks Fabio!
I didn’t even notice haha, I reseated the screws and they are now Front 2 1/2, Rear 3 1/4. Like I said still not perfect but it’s a lot better than it was, i still need to play with them as the revs hang abit when coming off the throttle and settling to idle which I think means lean? I just couldn’t figure out what cylinder needs tweaking and I ran out of time on it today so I’ll have another go next week.

just saying and you prob dont wana touch them again but your fuel screws are a fair bit rich, over 3 is a lot but if its runing good maybe just leave alone . my inner fiddler would take a half a turn in on both of them just to try

[LewisB]

just a we note. you have the front pilot screw and rear the wrong way round. . my old crusty memory says you want the rear one slightly richer then the front, no big deal running wise but the rear runs a tad hotter.

Thanks Fabio!
I didn’t even notice haha, I reseated the screws and they are now Front 2 1/2, Rear 3 1/4. Like I said still not perfect but it’s a lot better than it was, i still need to play with them as the revs hang abit when coming off the throttle and settling to idle which I think means lean? I just couldn’t figure out what cylinder needs tweaking and I ran out of time on it today so I’ll have another go next week.

just saying and you prob dont wana touch them again but your fuel screws are a fair bit rich, over 3 is a lot but if its runing good maybe just leave alone . my inner fiddler would take a half a turn in on both of them just to try

I did try taking them in but the bike didn’t want to go back to idle nicely after reving

[tony.mon]

I'd be tempted to try a different pilot jet size and retry, for that cylinder, to see if you can get it under three turns out.

[LewisB]

I'd be tempted to try a different pilot jet size and retry, for that cylinder, to see if you can get it under three turns out.

Maybe next time I have them off I will but it’s running okay for now I don’t want to mess with it haha

[LewisB]

Well it seems like some of my problems are back idling has become erratic again and coughing and missing but only at bang on 2.5k revs. Squirted carb clear to test the new boots again and the front boot has developed a leak I’ve done 100 miles on the new carb boots and made sure the surfaces where nice and clean. And the clamps are done up to the max!! Contemplating a thick coating of copper rtv silicone at this point. Anyone got ideas about other methods of curing the problem?

[sirch345]

Well it seems like some of my problems are back idling has become erratic again and coughing and missing but only at bang on 2.5k revs. Squirted carb clear to test the new boots again and the front boot has developed a leak I’ve done 100 miles on the new carb boots and made sure the surfaces where nice and clean. And the clamps are done up to the max!! Contemplating a thick coating of copper rtv silicone at this point. Anyone got ideas about other methods of curing the problem?

This seems rather odd to me. One would think if there was a problem with the quality of the new boots both would be showing that

Probably a stupid question, but are you sure the carbs and new boots were fully seated on assembly? both on the inlet manifold stubs and the carbs side,

Chris.

[tony.mon]

The carbs need to be pushed pretty hard into the adaptors, you can feel when they "pop" fully home. The first one goes in easy, but the second one is trickier.
A smear of red rubber grease inside the adaptors helps.

[8541Hawk]

I do agree that it sounds like the carbs are not fully seated. You can looking in from the sides and visually check if they are seated properly.

[LewisB]

Yep I made sure to take the time to seat the boots well, and I am sure the carbs went in all the way. They popped in and I had a lot of my weight pushing down to ensure they where seated correctly. I think I’ll take them all back off, give the surfaces another clean and try again. I am using the original fasteners so many I’ll nip to a shop tomorrow and replace them with new jubilee clips? But I did inspect and clean them and they seemed okay. I’ve ordered some copper rtv silicone so I will give them a coat of that as well because I’ve been scratching my head for a couple days and searching far and wide on the web and can’t seem to figure out why new boots are behaving like the old ones.

I should add, that it is the front one that’s been leaking, before and after replacing the boot. Unless it’s not the boot? But the leak must be very close to it for the carb cleaner to get in and stall the engine

[tony.mon]

Has the front vacuum take off been fitted?
That might be where the leak occurs.

[LewisB]

Has the front vacuum take off been fitted?
That might be where the leak occurs.

Yes I put a brass nipple and pipe (and a little thread lock) in it for balancing, but I sprayed that and it not that :/

[LewisB]

Is there anywhere on the actual carb near to where the boot sits that could leak?

[8541Hawk]

Yep I made sure to take the time to seat the boots well, and I am sure the carbs went in all the way. They popped in and I had a lot of my weight pushing down to ensure they where seated correctly. I think I’ll take them all back off, give the surfaces another clean and try again. I am using the original fasteners so many I’ll nip to a shop tomorrow and replace them with new jubilee clips? But I did inspect and clean them and they seemed okay. I’ve ordered some copper rtv silicone so I will give them a coat of that as well because I’ve been scratching my head for a couple days and searching far and wide on the web and can’t seem to figure out why new boots are behaving like the old ones.

I should add, that it is the front one that’s been leaking, before and after replacing the boot. Unless it’s not the boot? But the leak must be very close to it for the carb cleaner to get in and stall the engine

The down side to your plan is the petrol eats (dissolves) silicone

[LewisB]

I’m pretty sure the rtv silicone Ive got is fuel resistant. Plus it’s not like fuel will be coming out considering the vacuum is drawing air in through the leak