Bultaco model 92 big bore ? How big can you go

[larry s. k.]

Hi   Purchased a Sherpa m80 100 cc , on ebay few years ago ,just engine , Installed new piston please look at pictures ,small head ,don’t see any 100cc  , on m80 ,, what you think

[larry s. k.]

Bul model 92 pictures of engine in progress  I mk at 83.00  the bottom of sleeve look thin . So will check on other options. Or maby as is with new piston rings 

Edited December 29, 2019 by larry s. k.
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[model80]

OK, I’m completely confused by this post.

Have you got 1 engine or 2?
 

What exactly do you want to do?

[larry s. k.]

Hi ya have  2  listed I was looking for another 100cc model 80 and found one , so bultaco model 92 350 was wondering how big can I bore or replace cylinder with another that will fit  it’s at stock bore with original cylinder , by the book stock is 83.2 can I install say 360 cylinder ,  or any info just looking to trick more hp ,  

[feetupfun]

1 hour ago, larry s. k. said:

Hi ya have  2  listed I was looking for another 100cc model 80 and found one , so bultaco model 92 350 was wondering how big can I bore or replace cylinder with another that will fit  it’s at stock bore with original cylinder , by the book stock is 83.2 can I install say 360 cylinder ,  or any info just looking to trick more hp ,  

More HP? Have you ridden it yet? They are known for a few things but not for lacking power

[larry s. k.]

Hi  have not fired up this engine have some parts to complete , as a short block found a match cyl ,  would like find better cyl..yes would like make more hp , has good crank rod is ok , I had a model 213 running few years ago , it sat years old gas in tank , got it running after few hours cleaning  it was not very powerful lasted 3 hours and lower end &. Piston started scoring , and puffing out of carb , so I put this on back burner , would like to make fast 326 , if possible ,pursang parts big bore best ignition. , maby with some ideas ,,

[suzuki250]

Why would you want a fast trials bike? 

[feetupfun]

4 hours ago, larry s. k. said:

Hi  have not fired up this engine have some parts to complete , as a short block found a match cyl ,  would like find better cyl..yes would like make more hp , has good crank rod is ok , I had a model 213 running few years ago , it sat years old gas in tank , got it running after few hours cleaning  it was not very powerful lasted 3 hours and lower end &. Piston started scoring , and puffing out of carb , so I put this on back burner , would like to make fast 326 , if possible ,pursang parts big bore best ignition. , maby with some ideas ,,

The open class Pursang cylinder that fits that bottom end is also 325cc. The later open class Pursangs (360 and 370) have a longer stroke, as does your model 213 Alpina

[larry s. k.]

7 hours ago, suzuki250 said:

Why would you want a fast trials bike? 

Hills climb , race other bikes open dirt road ,around hear there old Loggin roads where  I started , with old Honda sl 90 with a straight pipe nice and loude , ,',,,,,,,,,,  ,I have a steep hill near home going to tackle it ,,, 

I 

[rcgods]

On 12/22/2019 at 4:43 PM, larry s. k. said:

Hills climb , race other bikes open dirt road ,around hear there old Loggin roads where  I started , with old Honda sl 90 with a straight pipe nice and loude , ,',,,,,,,,,,  ,I have a steep hill near home going to tackle it ,,, 

I 

Sounds like you need a motorcross / enduro bike rather than a trials bike for this particular task.  Ignore for a minute finding the cylinder to fit, the gearing of the engine will be all wrong and there is only so much you can do with sprocket swaps.

[larry s. k.]

Do you dig it ,,,, message 12 30 2019 , please  I. seem to say something a little off , please don’t take it personal   Just from states , thanks ,, 

Edited December 31, 2019 by larry s. k.
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[model80]

On 12/25/2019 at 2:34 AM, larry s. k. said:

Do you dig it 

Not really.

It sound to me like you need a Frontera, or a Pursang.

[bult360]

On 12/28/2019 at 12:55 AM, larry s. k. said:

Hi dublin Ireland , cool , I have variety of bikes ,yes like pursang frontera , I have  collection , projects  in different states of repair , like my own little work shop , I  pick up engines ebay , frame wheels , exc. purchase local Craigslist projects , when , price is right  ,, Noticed you like Sherpa , there very popular in Europe  , pursang is most popular  in states , I have model 68 runner not with original 68 cylinder it’s a putter  , think cyl off  Alpina 85 , it was a fixer  , I purchased Craiglist 4 years ago , 550, usd , had to drive 200 miles , purchased another gas tank original side covers  rear wheel new clutch , seat cover , ignition  and front fender pointy one , , have happy new year I

I

Hi , the equivalent year pursang (model 104 ) parts will fit straight on but the cases will need matching as the transfers are bigger on the pursang . you wont get 352cc mk7 or 363 cc mk8 pursang parts to fit as they have different stud centres plus they have longer stroke , not forgetting the airbox and exhaust , ignition and primary weights . Its a Sherpa T a trials bike , theres a reason Bultaco made the frontera and pursing , enjoy it for what it is .

[larry s. k.]