1994 501 cc to 551 cc

I would think the big end will cry if you do that but it is up to you. if i did it, i would dish the piston and lower the compression slightly. if you didn't know (and I'm sure you didn't), boring out on its own always increases the compression ratio.

why not look at the wossner site and find another european bike with a 97 or 98mm bore, 20mm little end and about 23.5mm deck height and then take out 9scollop out0 the middle a little.

regards

Taffy

so you only have 0.5mm of damage to the bore wall? they can often recover that. let the nikasil men see it and decide, yiou just have a 95-96 and 97mm piston ready to go.

looks good. because you have considered just 1mm on the bore, the cc will be 510. the compression will go from 11.8 to 12.1 to 1 and to drop that you need to take just 0.5mm out of the middle. you must leave a ring of 8mm around the outside. in all honesty, 11cc isn't much of a change so scolloping out the middle on this occasion is hardly worth it. get to a 97 or 98mm piston and it is a serious issue.

regards

taffy

I am currently working on rebuilding a 94 501 motor with a KTM RFS piston. I have a thread I started, which I will update next week, once I have the project finished or determine that it just won't work.

The KTM piston is 0.5mm taller - which means you lose 0.5mm clearance between the piston and valves. This has to be addressed, or the piston will likely contact the valves. I believe I figured out a solution, which I will share in my thread.

Presently, Wossner is the only manufacturer I am aware of, who makes pistons for these older Bergs. Being able to use a piston out of the KTM rfs motors will open up options for Wiseco, JE, Vertex, and ProX brands, with stock and high compression applications, in a 95mm bore. Additionally, perhaps relevant to you, is that the KTM rfs pistons are available in a 97mm overbore.

Well, I hate to kill the exciting news I planned to reveal in my own thread - but, that is the direction I am going.

The stock base gasket is 1.5mm. I had a custom .5mm copper shim made. I also found another supplier that provided me a quote to make a 2mm thick base gasket. However, the .5mm shim route was much cheaper, so that is what I am giving a try. Coincidentally, the stock KTM paper base gasket is .5mm. I ordered one, but after receiving it, I had concerns about it smashing down smaller than .5mm, once the head bolts are torqued down.

The only consideration in going this route, is whether there is enough slack in the timing chain for the added height. Once I received the .5mm shim, and realized just how thin it is, I do not expect it to be an issue.

I ordered a stock 95mm piston, which should arrive today or tomorrow. Again, I do not know whether this will ultimately work or not, but will soon find out and share.

VOR165

you make this sound like nuclear fusion, like the quatermass experiment? at the beginning I thought you were out to 'out tongue-in-cheek' me! and nobody does that!

these ol girls take a 1.0 - 1.5mm taller piston let alone 0.5mm!

and they don't have a base gasket after the early noughties?

yes, the cam chain can easily take a thicker base gasket - especially a worn one!

but now you are changing your cam timing!

and the valves are nowhere near the piston, they have at least 3-4 times the recommended minimum clearance you need.

far from american 'big-bore' why aren't you'll putting in a road and track cam, a squished dished piston, big valves and a heavily ported head and letting it breath!!!!

and even then, the big end won't be happy if you don't get all this and the ignition timing, the jetting and the thing set up nice. and the exhaust and .....

regards

taffy

you can't run the piston in raw aluminium! all husaberg pistons run in nikasil lined alloy barrels.

I have dozens of barrels coming in about 6-weeks!

but I'm not selling them for less than the OEM price would be.

Taffy

all Husaberg barrels are nikasiled alloy and they won't run in aluminium!

I have dozens of barrels coming in about 6 weeks.

Taffy

bbonde10 said:

Taffy,

Were the 1994 501 cylinders plated? You mentioned taking it to the nikasil guys for relating. If I just bore the cylinder, how will this compare to a plated cylinder?

I have access to a machine shop to bore the cylinder for free and would rather go this route than spend the money to get the cylinder plated.

Thanks,
Brandon

Click to expand...

I think you would have to press in a sleeve (liner) that could be bored. I don't know of anyone that makes sleeves for Husabergs.

You could contact LA Sleeve and see if they could match something up.

I would just have it replated.

I can tell you for a fact that it's not difficult to find someone who will make sleeves for these early Husaberg engines. The cylinders are almost identical to the later KTM RFS cylinders and guys have been boring those out and sleeving them for a long time.

As a matter of fact, I have a cylinder that Thumper Racing bored and sleeved for me to fit a 100mm piston. It's for a 600 so it's much taller than a 501 cylinder. I'm also using a custom Carillo rebuildable connecting rod and a Wossner piston for a 2008 550. With the stock 600 stroke, I'll end up with a 660cc engine. Currently saving up to have the head reworked with larger valves and the carb (a Keihin 41mm unit) properly set up. C'mon tax return!

back in the early eighties when it was becoming popular to have a jap mx'er with a nikasil lined cylinder, i got a bike in my shop from a fella who just had his kawi bored, and "now it won't run!".
so i figure they are good for about an hour before they self destruct

I do a 600 rod for anyone else who needs one. I sure as hell could do with selling one or two! I also have the 501 rod as well.

I've been told by 3 different people that the hot ticket is the early 501 longstroke in the 501 making 530cc. I met the guy that won the very last 'Haynes Four-Stroke Championship' and that's what they did. so it would be 95 x 75 for 530cc.

sadly, the Americans think bigger is better again even though the poor little things can't breath through their nasel passages and the big end will go at the first sign of overrev!

the re-mapped ignition we have done is a significant improvement and should be high on any tuners list but do they get it done? do they?? do they phuq!!!!

I have a krosskart 628 producing 100bhp and my 400 produced something like 52 rwbhp and yet people have no idea. Australian beach race winners as well!

so now these old bikes are at least 17 years old, people NOW sdtart to bore them out! that is like putting Ned at 75 into high altitude marathon training, with 20 year olds when all he wants is his pipe and slippers at his age!!

some people hey!

Taffy