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Old 06-29-2012, 06:43 AM   #196
blaine.hale OP
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Well, the thread on the actual monobloc AMAL body what holds the main jet service cap is stripped out. This means it won't actually hold that cap anymore and just dumps fuel everywhere. It's honestly not worth the trouble to find someone to add material and re-thread it.
I had a spare AMAL 932 (the original carb on this bike) laying around from the 2 Bandidos I picked up. Ordered a refresh kit and all new jets/needle for it. Just waiting on those and the chain to come in.
I think I might order some generic metal fenders and a tail light to get this thing tagged and ready to go for the summer.
I've had one latent issue that I've always pushed to the back of my mind because it's something I'd have to split the cases again to look at.
When I crank the bike and it's running, the kickstart continually makes that lovely ratcheting noise. You can hear it at the very end of the dirtbike video I made a while ago.

Sometimes, if I pull the kickstart forward enough, it will stop. Problem is, the kickstart spring isn't strong enough to do it on its own.
We'll see how that pans out when I get it consistently running.
At any rate, here's the fresh rubber on the front wheel.
Still need to clean the spokes and mount it up. Same with the rear wheel.
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Old 07-17-2012, 07:47 AM   #197
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Any thoughts on the above post about the kickstart?

I'm hellbent on getting it running this week. The new tires are on the rims, just putting the rear tube in tonight.
I got an AMAL 932 in last night. It's a right side brit one...which really doesn't matter much. The only difference between it and the Spanish versions is metric vs. british standard. Aside from the tools used for the brit version, it looks like the threads are the same as the metric and I can just use the Spanish AMAL jets and screws on it...am I wrong? They seem to thread in just fine but I don't want things to go wrong later.

Next step? Order the generic metal fenders and hunt down similar colored wiring and start making a loom to get this sucker street legal.
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Old 07-17-2012, 03:19 PM   #198
Jeffn
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Wish I could help out on the kicker buut will watch closely at your new loom as my 71 needs some low volt wiring too-looks like all you can eat linguini night right now.
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Old 07-17-2012, 03:30 PM   #199
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Main faultys for the kick starter are the springs getting old and loosing tension at first #5 and then #3 Problems with the ratchet gears are rare.




Metal fenders are a must have for your bike in my opinion.
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Old 07-30-2012, 06:31 AM   #200
blaine.hale OP
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Well, I somehow managed to seize the engine (new piston/rings) with out even getting to ride the sucker.
How can you tell if it's a crank bearing or the piston/rings seizing without splitting the cases to get to the bearings? I pulled the head but the jug seems to be stuck, so I assume it's the piston that's seized. Got it soaking in marvel mystery currently.
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blaine.hale screwed with this post 07-30-2012 at 07:18 AM
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Old 07-30-2012, 07:48 AM   #201
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New bore? if so, did you chamfer the ports and also position the rings so they don't hang up in a port. VERY VERY important on the 2 smokes.
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Old 07-30-2012, 07:58 AM   #202
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Quote:
Originally Posted by lrutt View Post
New bore? if so, did you chamfer the ports and also position the rings so they don't hang up in a port. VERY VERY important on the 2 smokes.
Nah, not a new bore. Just honed it as it was and put in the new piston and rings.
JUST in case, do you have an article on doing that? I need to cover all bases, heh.
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Old 07-30-2012, 09:13 AM   #203
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all 2 strokes I've worked on have a steel pin in the ring groove to keep rings from rotating. But I've never worked on a Bul before.

As for chamfering, if you just honed it you should not have a problem as the ports likely already have a small chamfer to them.
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Old 07-30-2012, 09:53 AM   #204
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Unless you have used an OE Mahle piston, your problems may have been caused by very poor quality replacement piston. There is small part fitted into the LH case, which takes the kickstart ratchet out of engagement whens returned to forward position by spring, if this is loose or worn it might be the reason the ratchet is noisy.
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Old 07-30-2012, 04:40 PM   #205
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My thought also about the ring stops...
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Old 07-30-2012, 06:30 PM   #206
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Think you guys are right.
Pulled the motor, freed the piston, checked the crank bearings and primary. All was good so it pointed to the piston. Pulled the jug, re-honed it (there were some not so perfect spots) and noticed that the piston had some side to side slop on the con rod.
Decided to put it all back together and back in the bike because everything was buttery smooth again. Started up in one crank so I began adjusting the carb for a proper idle. Locked up again.
At this point, I'm 90% sure it's the wrong piston size and the guys I ordered from didn't recommend the right one for the bore measurements I gave them. No big deal, I guess. I'm going to pull it again and measure the new piston vs. the old piston and the bore then post the numbers up here to see what you guys recommend. All I know of the top of my head is that it's a 250cc jug bored 1st over.

Really glad it takes all of 20 minutes to pull the engine from the frame ;)
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Old 07-31-2012, 10:38 AM   #207
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Quote:
Originally Posted by blaine.hale View Post
Think you guys are right.
Pulled the motor, freed the piston, checked the crank bearings and primary. All was good so it pointed to the piston. Pulled the jug, re-honed it (there were some not so perfect spots) and noticed that the piston had some side to side slop on the con rod.
Decided to put it all back together and back in the bike because everything was buttery smooth again. Started up in one crank so I began adjusting the carb for a proper idle. Locked up again.
At this point, I'm 90% sure it's the wrong piston size and the guys I ordered from didn't recommend the right one for the bore measurements I gave them. No big deal, I guess. I'm going to pull it again and measure the new piston vs. the old piston and the bore then post the numbers up here to see what you guys recommend. All I know of the top of my head is that it's a 250cc jug bored 1st over.

Really glad it takes all of 20 minutes to pull the engine from the frame ;)
I would recommen to measure the cylinder now after you have re-honed the cylinder a second time and then figure out which oversize piston you need. The oversize pistons come in +0.25mm steps. Normally the diameter of the cylinder is recorded on a lable on the box where the piston is delivered:

Here the first oversize piston for my Bultaco with 85.25mm in diameter and a given diameter for the cylinder of 85.28mm so there is 0.03mm clearance between cylinder and piston. (Sherpa model 199b 340cc ultrashort stroke engine)

Just for comparison the piston of my KTM, (a 500cc two stroke with steel sleeve), has 90.17mm in diameter and the clearance is given with 0.06mm between piston and cylinder. (standard stroke).

I would not take any rule of thump clearances get a standard oversize piston, get the cylinder honed until the clearance fit to your piston and you will get the engine running trouble free. (BTW: never had problems with Wiseco pistons so far ..., I can recommend Wössner pistons they even do custom made pistons for a very good price here in Germany)


PSchrauber screwed with this post 07-31-2012 at 01:41 PM Reason: this and that and of course I found some of the spelling issues I have
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Old 07-31-2012, 01:42 PM   #208
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I've never seen ordering a piston to the bore. You always buy the first oversize that will fit then bore to match the piston wtih recommended clearances. Sure the piston will fit but if there's only .001 clearance on a 2 smoke she will lock.

Need to take the piston (if it's still servicable) with the cylinder to someone who know how to do 2 strokes. Just any old shop won't do 2 strokes properly. Cast pistons require a different clearance than forged. You need to have the recomended clearances to provide to the machinist. You may also need new rings given the 2 soft siezures you've experienced.
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Old 07-31-2012, 01:53 PM   #209
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Great job man, can't wait to see the finished product. That is truly a work of art.
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Old 07-31-2012, 01:57 PM   #210
PSchrauber
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Quote:
Originally Posted by lrutt View Post
I've never seen ordering a piston to the bore. You always buy the first oversize that will fit then bore to match the piston wtih recommended clearances. Sure the piston will fit but if there's only .001 clearance on a 2 smoke she will lock.

Need to take the piston (if it's still servicable) with the cylinder to someone who know how to do 2 strokes. Just any old shop won't do 2 strokes properly. Cast pistons require a different clearance than forged. You need to have the recomended clearances to provide to the machinist. You may also need new rings given the 2 soft siezures you've experienced.
As the TO has now honed the cylinder twice and is still using the same piston there might be an issue, maybe he has now too much clearance between piston and cylinder and have to get the second or third oversize piston? Sadly we don't know the diameter of the piston or the cylinder.

Normally when you "overhaul" the top of an engine with an steel sleeve ... (my bad english ...) you get a new piston with has the next oversize. Then you normally give the piston and cylinder away for a rebore. The spec's for the clearance (as you see in the pic above) between piston and cylinder are given by the manufactor of the piston at least we in Germany do so. You should not only use new rings also a new piston pin the bearing for the piston pin and the clamps that hold the piston pin should also be replaced. (All these parts - at least in Germany, France and Spain - you get new when you buy a new piston).
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