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Bultaco "slimline" Help Needed!


scotty
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Ok guys I've taken the plunge and bought a early bultaco, as far as I know its a 71 (k reg) but it needs setting up correctly, it starts but its woolly! as in the revs are all over the place! It seems like air is entering somewhere. The inlet manifold rubber and the airfilter hose has got some splits in them? so these will need replacing for a start! An amal carb 627 type L428 is fitted and looks quite a new one! Is this the correct carb? whats the correct spark plug and ign timing?

Also I've included some pics as the front brake is much bigger than standard it looks like a mk1 cota front wheel? what do you think? I've had a m80 front wheel in the garage for ages (lucky I didn't throw it away!) but I need the front brake hub.

and when side by side the wheel that's fitted to the bike is much larger and a later model clutch cover has been fitted at some stage?

Thanks in advance guys!

internet1.jpg

internet2.jpg

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The slimline kit was first fitted to the m49, looking at the front pipe on your exhaust it looks like its from a m49. The front hub could be from a Pursang as this was a common mod. I would check the frame number to see if its a m49 or m80 frame. If you have the first issue of Classic Dirt bike my M80 is inside it may help you with comparisons. If not, pm me with you email address and I will send you some piccs of the bike if you want them. Best of luck with a classic bultaco, Mark

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627 carb is the correct type, as in 600 series, 27mm. You can still buy new Amals but only in 'even' number sizes such as 24, 26, 28mm etc. so unlikely it is a new carb unless someone had sourced some new old stock. Timing is personal preference really, anywhere between 2 and 4mm BTDC. Can't think of plug type of top of my head. NGK BPES6 or 7?

Front wheel doesn't look like an early Cota as they were massive hubs, could be an early Pursang. The lug on the left of the brake plate showing behind the fork leg looks like it is the cable mount as the earlier Sherpas and Pursangs up to about '72 had the brake arm pointing rearwards under the fork leg. Type 91/92 Sherpa onwards had them pointing forwards with the cable locater on the bottom of the torque arm.

Clutch cover definitely off the later model but you'll easily pick up the correct type if you're bothered.

Yours looks like a type 80 but the front exhaust pipe looks like a 49 type as it is straight across the top instead of bending down to meet the silencer. Instead, the silencer (Sammy Miller one) has been modified with a bend to meet the front pipe. Love the alloy back box, Miller again I think.

Nice straight bike on the whole which wouldn't take much to make 100% original if that is what you want to do

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Hi Scotty: First of all it is important to know the model. Can you check both frame and engine numbers??

The 2 first digits are the model number, and they should be the same. Knowing this I can help you with your bike.

It looks to me as a model 80 or an early model 91 or 92. But maybe it is a model 49 with a lot of later pieces in it.

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ok the frame is B80-002837 engine M80 -002838 keep the replies coming lads as im not so clued up on the early spanish stuff! didnt know the alloy REAR silencer was a SM one ? :wacko: on the above info is this a model 80 slimline? 1971? and should i keep the big hub or revert back to the smaller std type?

also gonna try to get used to that left side brake!!! :D

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There's an M80 wheel on ebay at the moment. I know you have one already but if it comes at the right price and has a brake plate (doesn't say) it solves your missing brake plate problem. Item 230090795724.

Yours is a model 80 slimline which is 71/72. I'm guessing the rear silencer is a Miller one. It's not original as all Bulto one's were steel and that shape was fitted to later bikes anyway. The original type would have been the triangular silencer that everyone threw away (and now wants again.... although you can get new ones again now) There is a mounting lug on the rear of the rear frame tube under the top shock mount which is for the triangular silencer. Model 80 was the first to have this.

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Thanks for the pics! but what of the large front brake keep it or fit the std one. Like i said ive got the original wheel minus brake hub! also should i keep the rear silencer on it ? proberly best to keep the noise down! may have a word with dave at bultaco uk about a front hub or look for one at the malvern show on sat! :D

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Thanks big john, your proberly right on this as i cant see a few cracks in the inlet gasket/carb airbox hose could affect it that much! the revs go a bit wild with not much reponse from the throttle plus it takes a few kicks to get it going! can i change the mag side seal without splitting the c/cases?

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Yes, the Bulto is a handy design in that the seals are held in carriers which bolt onto the crankcases from the outside, so no need to split the engine. Just unbolt the carrier, replace the seals and refit (either side) Crank seal went on my Ossa today, just hoping that I can dig it out and replace it without splitting the engine.

Edited by Woody
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