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MK1 carb tuning and BTH noise?

Ducdude

Well Known and Active Forum Website User
VOC Member
Today I took the 52 shadow on a 50-60mile high speed 60-90+mph hop and I am happy to report that the bikes manors around town and on the highway are indeed improved with the needles all the way up. Smooth idle and good steady acceleration to 60-70mph with no stumbling or missing...

The bike still only tops out at 90-95mph , depending on the wind and seating position, she just runs out of steam. My next step is to go up from the 210 main jets to 220s and see if that gives me a bit more on the top end...I have up to 240 size jets in inventory but I think it may be wise to just take it in steps...Data point- a new compression test shows 149-150psi on the rear cylinder (was the leaking one at head joint now fixed) and 154-156psi on the front...

Comments and recommendations welcomed...


Now I have about 400 miles on this bike since I put her together after 40 years of slumber and I have a BTH on her which seems to be doing its job just fine. Today's temp was in 77F/25C and this was the first run in temps this high while really pushing her. After she was good and warm after 50 miles at 70-80mph avg., I exited the motorway I noticed an RPM dependant whine coming from the front of the bike. Not scary sounding and not a warbly whine just a whine that varied it's pitch with RPM.. I had thought primary chain but it is not coming from there and that chain already has a bit of extra play in it from the last time I heard this whine...last fall

So, the question is as I have never had a bike with a mag in it or a Vincent before are they prone to whine a bit when at opperating temp or should I start thinking that the BTH's bearings are starting their death song...

Another possibility is the gear clearances in the timing case could be a bit to snug and once at summer operating temp and the related expansion is supposed to sound...

Thanks for any and all comments and suggestions..

It was a glorious day to own a Vincent!

I hope you all got out and enjoyed it!

Ciao,
Eric
 

Albervin

Well Known and Active Forum Website User
VOC Member
Eric, the source of noises, like oil, can be deceptive. Check the generator drive. It can often be a source of a whine, just before the centre row of the primary chain is ripped out! It could also be a bush or thrust washer in the timing chest that is protesting. Just don't be too keen on getting those high top speeds. When you own a Vincent you don't have to prove anything. It is much more satisfying using the torque between 60 and 80 mph on a country road.
 

b'knighted

Well Known and Active Forum Website User
VOC Member
Are you running with both fuel taps open?
Running on just the left tap is fine for the sort of riding Albervin recommends and this leaves the right tap as reserve.
You may find that you need to open both taps to run at higher speeds.

Cheers,
 

Bracker1

Well Known and Active Forum Website User
VOC Member
Check out Irvings, "Tuning for Speed Article" on jet sizes for carbs. I do believe he references the cams and exhaust as well. Might just be a clogged silencer. What goes in has to come out. Safe Riding, Dan
 

davidd

Well Known and Active Forum Website User
VOC Member
Albervin has suggested the first item I would check: the generator drive. It is unusual for a mag to cause a whine, it is almost routine for a generator sprocket to whine.

David
 

Ducdude

Well Known and Active Forum Website User
VOC Member
Eric, Check the generator drive. It can often be a source of a whine, just before the centre row of the primary chain is ripped out! It could also be a bush or thrust washer in the timing chest that is protesting. Just don't be too keen on getting those high top speeds. When you own a Vincent you don't have to prove anything. It is much more satisfying using the torque between 60 and 80 mph on a country road.


Thanks Al... The Gen gear is a poly gear and the gen is freshly rebuilt with new bearings and is spinning true and well...The whine is coming from the area of the BTH mag....Which has a white poly gear that has a history of swelling when hot. I did not leave much slop in the timing case when I built it up so even a few thousandths would surly be an issue I have a new mag gear coming and so now it is back into the timing case. As for the high speed runs on the Shadow, I do not intend to run her often at the ton or more, but darn it if I can get here running well enough to do it then that will be my goal ...


Cheers,
Eric
 

Ducdude

Well Known and Active Forum Website User
VOC Member
Are you running with both fuel taps open?
Running on just the left tap is fine for the sort of riding Albervin recommends and this leaves the right tap as reserve.
You may find that you need to open both taps to run at higher speeds.


Ian,
I have been using both taps for any of the motorway high speed stuff....I have also installed high flow 1/4 bore petcocks just to be safe. Sadly I am only getting 100 miles per tank and I doubt this will be getting any better as I keep razing the needles and putting in bigger and bigger mains, in the quest for a higher and higher top end...:)

Cheers,
Eric
 

Ducdude

Well Known and Active Forum Website User
VOC Member
Check out Irvings, "Tuning for Speed Article" on jet sizes for carbs. I do believe he references the cams and exhaust as well. Might just be a clogged silencer. What goes in has to come out. Safe Riding, Dan
1952VincentBlackShadow_wallpaper.jpg
Hmmm now there is a good point look at the pipes on my shadow at the union....Could the blueing be a restriction??? Could be...Will have to have a look at that....

Thanks Dan,,
Eric
 
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