Bultaco 199b

[scot taco]

I thought that I read or heard that the M92 had a different cylinder head design which gave it a more aggressive power delivery than the later bikes and that the 159 was also a bit more aggressive than an 199A?

 

[trialsrfun]

20 hours ago, woody said:

They run virtually out of the box on any bike. Generally the most you have to do is alter the pilot and move the needle one notch, can't remember which way or what pilot I've used (somewhere around 45 maybe) but it may be in the forum somewhere. A box of pilot jets is pretty cheap in the 32 - 50 range which you could order with the carb.

Thanks Woody, have you tried both OKO and Mikuni to get a comparison.

I have had a look on the website you suggested is OKO K101 26mm the correct type?

Edited February 13, 2017 by trialsrfun

[stevem75]

I had a 159 and used it for several years in regular competition.  I had a mikuni round slide 28 on it and the bike had really really sharp power delivery. Lots of snort.  Its was almost too sharp and would get me into trouble sometimes in the sections.  I then got a 199B and also used it in regular competition.  It was a much better bike I thought.  The chassis seemed better, not sure if thats the box swing arm being stiffer than the 159.  The frame geometry was likely the same.  But it just rode better all around.  Much smoother power delivery and easier to handle. I used a flat slide mikuni 28 on that one.   I too regularly broke the "fork type" head steady.  I eventually had a piece of cold rolled steel welded to it and that cured the problem.  The triangular brace is obviously the superior set up.  I've not tried a 199A but would suspect it has a more "developed" feel than the earlier bikes.  I did have a M80 for several years as well.  It had a great engine but chassis wise I didn't care for it.  I've also had a 92, same thing but better motor.  I had for a very short time a 151 and quite liked everything on it .  I think this is due to the frame being updated and the use of chromoly tubing and having the better exhaust on it.  

Steve

[woody]

1 hour ago, trialsrfun said:

Thanks Woody, have you tried both OKO and Mikuni to get a comparison.

I have had a look on the website you suggested is OKO K101 26mm the correct type?

I use a 28mm on the 325/340 engines that had a 28mm Bing originally. Mikunis work fine if you can jet them but they are a pain in the a*** to jet (for me)  If it isn't jetted right when it comes it's a lottery what to change if it's the mid range that's out due to the endless needle / needle jet combinations they have.  I've found the OKO is almost right as it comes on virtually everything I've fitted it to and just needs minor change to pilot and needle position.   If both are jetted right then I doubt either is better than the other - apart from the price

This is the one I use

http://www.ebay.co.uk/itm/OKO-28mm-RACING-CARB-FLAT-SLIDE-CARBURETTOR-CARBURETOR-/301495710655?hash=item46328b73bf

and one of these

http://www.ebay.co.uk/itm/SET-10x-SLOW-JETS-Tuning-PWK-Arreche-OKO-Carbs-LOW-SCTZ-/262647291462?hash=item3d26ff9e46

[woody]

3 hours ago, scot taco said:

I thought that I read or heard that the M92 had a different cylinder head design which gave it a more aggressive power delivery than the later bikes and that the 159 was also a bit more aggressive than an 199A?

 

The 92 has a lot of raw power and pulls like a train. It isn't more aggressive than later bikes but it is a lot harsher in feel with more vibration,later motors are smoother.

The 159 is aggressive due to the light crank weight. As the 183 and 191 are virtually the same bike I'd guess they are too but never ridden one of those.

[woody]

3 hours ago, chappo said:

I also have a 198a (250) that has electronic ignition and a Mikuni fitted which is really crisp on the throttle and after riding my new 199b (albeit not for long) there's wasn't an earth shattering difference. Possibly when I get it run in and get an Oko fitted it may change. It was running very rich on the Bing.

Smelling 123, did your Oko come already jetted or did you have to make your own adjustments? Was it from an EBay source?

Thanks all for your continued assistance.

Dave.

The big difference between the 250 and 325/340 is the pulling power of the bigger bike which can use 3rd where the 250 can't (not often needed and probably never in today's classic trials anyway)  The 198b actually picks up and revs up quicker than the 340, again, due to a light clutch weight.  They'e all got enough power, 250 / 325 / 340

If you're looking for OKO carbs at Telford watch out for copies. Google OKO copy to see the difference. Even the box is a give away in the way the writing wraps around the corner at the bottom. On the copy the writing is set further to the right, so less 'text' on display on the front of the box. Plus the genuine OKO doesn't come with spare jets (the jets are different in the copy as well)

If your Bing is set right and not worn out, you're not going to notice any difference with the OKO or anything else

[woody]

39 minutes ago, stevem75 said:

I had a 159 and used it for several years in regular competition.  I had a mikuni round slide 28 on it and the bike had really really sharp power delivery. Lots of snort.  Its was almost too sharp and would get me into trouble sometimes in the sections.  I then got a 199B and also used it in regular competition.  It was a much better bike I thought.  The chassis seemed better, not sure if thats the box swing arm being stiffer than the 159.  The frame geometry was likely the same.  But it just rode better all around.  Much smoother power delivery and easier to handle. I used a flat slide mikuni 28 on that one.   I too regularly broke the "fork type" head steady.  I eventually had a piece of cold rolled steel welded to it and that cured the problem.  The triangular brace is obviously the superior set up.  I've not tried a 199A but would suspect it has a more "developed" feel than the earlier bikes.  I did have a M80 for several years as well.  It had a great engine but chassis wise I didn't care for it.  I've also had a 92, same thing but better motor.  I had for a very short time a 151 and quite liked everything on it .  I think this is due to the frame being updated and the use of chromoly tubing and having the better exhaust on it.  

Steve

I've compare the porting of a 199B, 199A and a 159 and they were all the same. If there is a difference, I missed it. The 159 is more aggressive due to the lighter clutch weight. Fit a 250 ignition flywheel and clutch weight to the 199A or B and either will spin up everywhere

[smelling123]

3 hours ago, chappo said:

I also have a 198a (250) that has electronic ignition and a Mikuni fitted which is really crisp on the throttle and after riding my new 199b (albeit not for long) there's wasn't an earth shattering difference. Possibly when I get it run in and get an Oko fitted it may change. It was running very rich on the Bing.

Smelling 123, did your Oko come already jetted or did you have to make your own adjustments? Was it from an EBay source?

Thanks all for your continued assistance.

Dave.

Yep from eBay, as woody said, scooter assassins is the seller. Flat side, no power jet.

i subsequently got a 48 pilot jet but otherwise great straight from the box.

[bondy]

Chappo yes the seller is on EBay and you can run them out the box as I did think stu did put another pilot jet in but only as he said he was being abit fussy .

[mrb505]

Woody I'm pretty sure all the 325's from m125 on had the same flywheels around 2.8 kg on both sides your 159 may have been modified if it had a pursang primary flywheel

[woody]

I can't be sure but it would explain why the 159 I owned and the one my mate owned had a much quicker pick up than any other model I've ridden. The only one that comes close is my 198B which also has a Pursang type weight on it.

The 159 we had made our other mate's 151 feel docile by comparison.  From the 159 on I don't think the engines changed much. As the porting seems the same on all of the 159 on 325 / 340 barrels, and I can't see the slight differences in the exhausts having such an affect, the only reason I could think of was lack of weight. Unless it was done by smaller ports in the crank case mouth and crankcase compression?

[sherpa325]

All the 325 powered bikes I have owned had the heavier flywheels on both sides, including a 159 and a 191, all owned from new. From the 159 onwards the engines pretty much all perform the same in my opinion. Differences in bikes I would put down to the type of carburetor being used  and also the timing of the ignition system and general freshness of the engine. Bings make good power but I always found them finicky, Mk 2 Amals are better off the bottom but not as strong up top [27mm] and wear out quickly, Dellortos are good as are the 28mm keihin flatslide. I purchased an oko [keihin knockoff] off ebay and could not get it to work at all and ended up throwing it away and replacing with a genuine keihin. The keihin is smoother than the dellorto and makes more top end and is pretty easy to jet, however I didn't spend as much time as I should have on the Dellorto as flatslides became legal where I compete. I have tried to use Mikunis  in the past with varied success, I found them really very smooth but always thought they were lacking in power in comparison to other brands - just a personal preference thing. By the way a friend has a 28mm flatslide mikuni on his 159 and it runs really well with plenty of power.

[nigel dabster]

13 hours ago, woody said:

I've compare the porting of a 199B, 199A and a 159 and they were all the same. If there is a difference, I missed it. The 159 is more aggressive due to the lighter clutch weight. Fit a 250 ignition flywheel and clutch weight to the 199A or B and either will spin up everywhere

Does the 199b not have different transfer ports and (originally)piston windows? @woody

[woody]

All the same on those I've had, the bigger pistons are used to keep boring out the 325 so if they were different  they wouldn't work effectively (I'd guess)