Kawi2strokes.com Forum

Just wanted to post some stuff.
Im not really sure what Im looking for except maybe some general info so I can put this all into perspective.
I dont know what to expect from these bikes and it has been a very interesting and somewhat frustrating learning curve.
I still don't have the jetting right but I think I am trying to achieve something that may not be achievable.
Below is a port map Moo did when he had my cylinders.
Any thoughts on how the power curve/ behavior would be with this porting would be appreciated.
I have researched it myself a bit and although I am confused I think I have at least a small understanding.
I am hoping this will help me learn a bit more in general.
I have read a bunch but none of it tells you about the manners or behavior of the power curve unless you have experience.
Right now it will not pull redline in 4th or 5th doing roll ons but Im sure its the VERY large main I have in while I am trying to get the needle right. On the needle between 4000 and 6500 it accelerates steadily but slowly in both 4th and 5th, I have tried every needle position and both p-5 and p-2 needle jets. The p-2 with the needle on the 2nd position seemed to work best but the changes where so small there was nothing drastic to suggest that it was MUCH better with any of the combos.
I don't know how they accelerate and from the dyno charts posted here there isn't much power in that range so maybe thats it and I should move on to the main. If I accelerate right thru the range it will pull red line but I have to keep it above 6500 to keep accelerating, if Iet it drop below 6000 I have to down shift to get the revs up above that again, I am thinking this is normal behavior for this bike with this porting, pipe and reeds, and although getting the jetting better will help it will still be this "flavor" if you get my meaning.
The pipes are Spec II.
(at least the Zeel is working better )
Thanks

How does it pull from 2,500 to 5,000 rpm?

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If it surges, that's normal, upshift.

Pulls fine, nothing spectacular, revs nicely.
It bogs right off idle a bit gets worse when hot.
Pulling away from a stop up any slight hill requires a bit of clutch slip and throttle

Just wondering, since mine pulls like a 4-stroke to the powerband, when it pulls way harder. Other than the flat spot around 5,200 rpm, that is. You should be able to tune away all the boggy spots.

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If it surges, that's normal, upshift.

Your port map points to a quite streetable H2 demus. This should work out quite fine, not radical at all, but remember your pipes are quite revvy I think, but I am not sure as I have not dynoed them.
But be aware of that 34 carbs on a ported H2 with pipes are VERY small. At least I had success adding 38's instead of those rather tiny 34's.

From your description, it seems like you have a huge flat spot right before you are in the powerband, since you need to be at 6500 to be able to accelerate. That is same behaviour as I had running 34's, Aylor reeds and pipes, and I could not get rid of it. (even tried the moderate higgspeed pipes, but the huge flat spot was still there, but I had great peak power, 109 rwhp with them jollyes, and 90 I think, with higgspeed)

I have the dyno curve somewhere of both vm34 reeds higgspeed and jollymoto comboes somewhere, but it is not really combarable to yours as the ex duration was 200 degrees, with ex port wider and more square for better blow down area and stronger exhaust pulse, and also the transfer duration was higher

..j.

Jørgen

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72 H2, 72 H1B, 74 H2, 74 H2 Cafê Racer, 71 F8 Bison

Hope to get all the bogy spots gone! It would be a lot better.
The question is what kind of four stroke does it pull like..the only comparison I can make to it right now in the rpm range 2500 to 5000 would be the old yamaha 400 special I had around for a few years, it may be a touch better than that but not a lot.
And I sure don't pull like the Harley I rode yesterday that thing will pull you arms off in 5th gear from a rolling start at 20 mph!!
Please don't take the comments as anything but me trying to figure this bike out with NO experience with it.
Once it gets to 6000 to 6500 it turns into a different animal, and once I get the main sorted out that will be even better!



From what I can tell with the way this was set up with the porting and the pistons which had 4mm cut (don't matter now with the reeds and the holes in the sides pistons ) and the Spec II pipes which were all part of the "package" PHR sold my cousin it was meant to be driven at a high rpm. And this would have suited my cousin well he liked riding every bike he had to its limit all the time, what ever that limit was he would be there. When we were kids riding I had to promise my mom I wound not try to keep up…I couldn't anyway but I tried . He even beat me in the twistys once on a Harley Soft Tail and I was on my Suzuki GS1150, both bikes are pigs... but a Soft Tail…

Anyway with the flat spot I assume changing needle heights and such would have little affect in that area, is that correct?
If I am trying to jet the flat spot (which I think I am) am I going to mess up the jetting somewhere else?
I think I am understanding why then you would want to be the richest you can be on the needle without burbling and problems.

Im moving on the the main jet and then I will play with the needles again later. I may just have to get used to the way it works, I dont think I can afford to switch it back to no reeds, although I would be neat to have another one with big carbs and good porting and a good pipe ..someday maybe.
Not being able to accelerate on the free way above 75mph sucked, I either had to be revving the crap out of it or just suffer in one spot hope that changes with the main jet a bit.
And I saw your post about warming it up and its very true I was surprised how different it ran once it really got hot and my 15 mile test runs from home when I was testing jetting are not enough to properly heat it up.

Some observations & comments....

It appears that you are chasing your tail by altering timing prior to getting jetting sorted.
I would set timing at stock 23deg, sort out jetting, then alter timing afterward.
Trying to play with two variables at the same time can be overwhelming.

Jetting can be time consuming and require a lot of brass. Your bike would probably be best suited with larger carbs. If that is what you want to do, now is the time to do it. Otherwise, if larger carbs are fitted you will have jetting to do all over again.

You reference rpm for jetting problem areas... it might be best to use throttle position as that is what the carb sees for various tuning circuits. Mark throttle position with tape for reference.

A chart on http://www.3cyl.com/mraxl/manuals/carbtune/carbtune.htm shows the overlap between carb circuit variables.

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Answers are here: http://kawatriple.com/

Completely agree with the timing Now that I have the Zeel figured out, and the fact that altering the timing by even 1 deg (at least in the lower rpms) changes things, I now have it set at what I hope is a bit more like stock. Starting at 21 at 1000 rpm and advancing to 23 deg by 3000rpm and then staying there until 6000 then rolling it back to 19deg at 9000. It seems to like that curve.
I am leaving it there until I get the jetting down.
I have the throttle marked and the problem areas are bogging off line, 1/8 to 1/4 throttle seems to burble a lot there, and then 1/2 to 3/4 Im having trouble deciding what needle position is best, not a lot of change when I change clip position, I do know when its to rich and to lean but there seems to be a two needle clip positions that work the same, thinking I should stay in the rich side of the settings,
The main right now is 310 and way to rich.
I have been going to bed with the carb charts in my head! I will persevere and get this right! (I hope)

The larger carbs won't work with Johns reeds I dont think . And I don't think I can remove the reeds without new cylinders and I am a bit worried about losing low end power, the bike will scoot around town at 25 or 30 in 5th without any problems and it will accelerate from that low without hesitation which I don't know if it can happen with piston port. ( I don't want to start a debate )

You just hear about all the "I can't keep the front wheel down" and the "throttle is so crisp"
Right now unless I get it above 6000rpm I just don't see that happening with this set up.
Above the 6000 or 6500 and it goes like crazy!
But remember Im not a 2 stroke guy and have no experience with them so my comparisons suck, Im used to my 1260 Suzuki Gs with fairly large cams and lots of porting, where in any gear at any speed full throttle can get exciting pretty quickly .
I think at 8000 rpm or so the H2 is accelerating nearly as quick. If I were to race this H2 I would be damn sure not to let the rpm drop below 7000!

The place to start is with the pilot circuit.... sounds like it is too rich.
If it is too rich then the needle won't do what is intended due to the overlap.
Have you adjusted air screw for highest rpm?
Have you tried a smaller pilot jet?

You should ask John about carb size... I think you can run 38's without any problem.

PS: Try a 250 main with 30 pilot on VM34"s, 6DH4 needle - 2nd clip

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Answers are here: http://kawatriple.com/

Totally agree with mraxl in everything he says. And yes, 250 mains sounds very reasonable if you are not living on top of a mountain or something.
And 6DH4 just cannot be wrong for your set up, stick to that needle. I am a bit unsure of your P2 needle jet. Try P4-P5, and you will probably be in the right ballpark. P6 is usally too rich.

And believe me: If you feel your bike is going as a rocket in powerband, full throttle, with 310 mains............ooooolalaaaaaa, can't wait reading your next comment when you have jetted down significantly. Yeah....250-260, go for it and prepare yourself for a 1.st gear powerwheelie!!!!!

..j.

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72 H2, 72 H1B, 74 H2, 74 H2 Cafê Racer, 71 F8 Bison