Tuning carb

[Duccout]

Hi Ian,

Lucky that you found it in time! I don't think that Loctite on the taper is a good idea as you may never get the flywheel off again. I remember Nigel writing that he tests the flywheel fit by tightening the nut and then taking it off again and seeing how much pressure the puller requires to pull the flywheel off. Nigel also said that the taper must be spotlessly clean. I always tighten the nut and then leave it overnight and re-torque next day in case something has settled; whether this is necessary I don't know.



Colin

[blethermaskite]

I wouldn't put loctite on it either, get some VERY fine grinding paste and lap the flywheel to the taper...as long as the tapers are good you won't need very much to achieve a nice even matt finish to both surfaces, it is absolutely essential that you scrupulously remove any traces of grinding paste from this job with thinners or brake cleaner or some suitable solvent......once the retaining nut is tight again only an extractor will get that flywheel off again. Cheers George

[IanHood]

Thanks gentlemen. Can someone remind me of the torque setting for the nut (or is it just 'effing tight')?

Ian

[Duccout]

According to Nigel, 95nm.

[IanHood]

Fixed it however I did have to buy a new flywheel from Electrex. I couldn’t get a decent mating with the old one despite the lapping. Looking forward to getting the old girl out in this sunshine

Ian

[NZ450Colin]

Hi Ian,

I'm looking at changing over to a PHBH 30AS from my existing VHB29AD. Assuming you still have the PHBH30 fitted, are you happy with how your 450 is running with it's current setup? Can you confirm what you have in there, particularly the slide, needle and atomiser. Is it just the standard delivery R4047 items from Eurocarb ( #40 slide, 268T atomiser and X8 needle)? Jet sizes you have would be good too, as a starting point.

My Standard 1974 450 desmo runs OK on the VHB29AD, but a good idle has always been a struggle both in the past with points and even now, after I fitted an Ignitech ingition, (which is properly set up and programmed so no problems there). It also won't rev out much beyond 6000 or so in top, (with 13 tooth front sprocket). I'm looking for any improvements really, but realistically, mostly a better idle.

Any feedback would be greatly appreciated.

[IanHood]

Hi Colin,

I wish I could help but I’m afraid I’ve gone back to the standard VHB. I’m sure it’s possible to get the PHBH working well but I’m afraid I couldn’t manage it.

Ian

[NZ450Colin]

Hi Ian,

Thanks for your reply. That is a shame. Are you possibly able to tell me what the PHBH had in it that didn't work for you and in what way it didn't work well? Even that would be a help. Assuming you bought it from Eurocarb, I'm guessing that it started out with their standard offering of #30 slide, X8 needle, 268T atomiser with #45 idle jet and main jet of 120?

Thanks for your help.

Colin.

[IanHood]

Hi again Colin,

Yes, I started with the standard issue from Eurocarb. The bike started well and ran nicely up to about 3,500 rpm but then ran out of steam. I went up a number of jet sizes (beyond what eurocarb supplied) until the bike would rev into the upper range but then I had issues with quickly fouling plugs.

Ian

[NZ450Colin]

Hi Ian,

Thanks for that. Interesting. I'll have to think this one over. Given my bike runs pretty much OK and I'm realistically probably chasing only small improvements, I don't want to buy the carb and then find myself in a similar position where I just can't even get it to work as well as what I already have. Especially if I have to start 'suck it and see" experimenting with the slide, needle/atomiser which would start to add up. I've run mine for around 30 years on a VHB29AD, but as an experiment just because I had one, recently fitted a VHB30AD from my Aermacchi 350 and with some minor tweaks, this is performing slightly better. (seems to have a bit more pull in mid-range). Anyway, I'll have a think.

Thanks again and if I have any specific questions, I might get back to you again.

Colin