Why would you want a H1 to run like a normal motorcycle??!
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| 1970 H1 Mid-Range Flat spot http://www.kawi2strokes.com/forum/viewtopic.php?f=14&t=14381 |
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| Author: | Thylacine [ Sun Feb 14, 2021 7:33 pm ] |
| Post subject: | 1970 H1 Mid-Range Flat spot |
Hi All, Seeking thoughts on an issue with my 1970H1. I have a big hole in the power band between ~4500rpm and 6000rpm at anything above half throttle, sounding like a rich misfire on one or two pots. Pulls fine above and below this. Am assuming this isn't normal, and makes for hard work cruising, as it can't hold against the slightest hill or head-wind in either 4th or 5th gear. Bike spec: was purchased as non-runner with rough home-made expansion-chambers, which I pulled-off, and fitted a set of replica original exhaust pipes from mid-Atlantic Cycle. Flat spot appeared when I got it running, including new pipes fitted. Has original airbox, and I've fitted replacement original style element from Jessbikes (made no change). Carb jets checked and all original spec/numbers. Next step was to fit replacement needles/jets in case previous owner had modified them to suit the old pipes. Any ideas out there? Cheers |
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| Author: | Jim [ Sun Feb 14, 2021 8:30 pm ] |
| Post subject: | Re: 1970 H1 Mid-Range Flat spot |
When it's having the problem, push the enricher lever and see if it gets better or worse. My guess is it's too lean in your flat spot. |
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| Author: | battleax [ Mon Feb 15, 2021 9:14 pm ] |
| Post subject: | Re: 1970 H1 Mid-Range Flat spot |
My H1A had a pretty good flat spot, a lot cleared up with an Ivan’s jet kit, key was probably the new needle jet. The stock jets wear quickly. Also Keep in mind in stock form, they are pretty sad off the pipe. I made it my mission to get my H1A to run like a normal motorcycle off the pipe, not being too concerned with absolute originality. I installed individual 90° elbows between the carbs and individual foam filters, machined squish bands in the heads and recently added a programmable ignition controller. Pulls in the midrange at least as strong as my H2. But it doesn’t look completely stock. |
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| Author: | RODH2 [ Mon Feb 15, 2021 10:33 pm ] |
| Post subject: | Re: 1970 H1 Mid-Range Flat spot |
Why would you want a H1 to run like a normal motorcycle??! ( )
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| Author: | Thylacine [ Mon Feb 15, 2021 10:39 pm ] |
| Post subject: | Re: 1970 H1 Mid-Range Flat spot |
Thanks both for the replies. Shall try the choke trick. It definitely feels like a fault as it will accelerate up to 4500rpm cleanly even in top, and then hits a brick wall followed by spluttering. Only way to get through it is to drop 2 gears to get 6000rpm+. I've seen reference to 'Ivan's Kits'. Does anyone have details + contact info? Cheers |
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| Author: | Jim [ Mon Feb 15, 2021 10:53 pm ] |
| Post subject: | Re: 1970 H1 Mid-Range Flat spot |
Thylacine wrote: I've seen reference to 'Ivan's Kits'. Does anyone have details + contact info? Information is in the vendor's section of the resource site, under "specialty". http://www.kawatriple.com |
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| Author: | ALTERED IMAGE [ Tue Feb 16, 2021 7:59 am ] |
| Post subject: | Re: 1970 H1 Mid-Range Flat spot |
Most ex chambers will have a wider flat spot. Gizmos like EXUP and power valves help. Boost bottles and such help also. As explained, bad vibes(RPM) between on and off the pipe(in between) BattleAx has one fix apparently. I think it shifts these bad vibe RPM points higher/lower and /or spreads them out so no that noticeable. Just the nature of the whole system. IMHO cliff |
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| Author: | battleax [ Tue Feb 16, 2021 8:36 am ] |
| Post subject: | Re: 1970 H1 Mid-Range Flat spot |
RODH2 wrote: Why would you want a H1 to run like a normal motorcycle??! ( )I was being as kind as I could, stock, particularly the early H1s, they are nearly unrideable until you find the powerband. Many people (even recently) have suffered numerous crashes, injuries and worse due to the all or nothing nature of the power. I prefer to ride in a controlled fashion, with a strong midrange, not needing to downshift for every bump in the road. Thus, to enjoy the motorcycle off the pipe but still have the famous 2 stroke rush when I wring it’s neck! |
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| Author: | H2RTuner [ Tue Feb 16, 2021 1:32 pm ] |
| Post subject: | Re: 1970 H1 Mid-Range Flat spot |
Please verify float level in carbs, and number on jet needle, along with which clip position. If you have the carbs torn down, also please add slide cut away (on bottom of slide, like 2.0, 2.5, etc), needle jet and main jet. Also, the jet needle is retained through the top of the slide, with a round plate that fits on the slide, and is held in place with the return spring that holds the cable in place. The needle clip fits between the slide and cable round retainer plate. Lots of incorrect little things can make for rotten performance. |
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| Author: | Thylacine [ Wed Feb 17, 2021 7:36 am ] |
| Post subject: | Re: 1970 H1 Mid-Range Flat spot |
Cheers H2RTuner. What’s the correct float height measured from bottom of carb gasket joint? Have read 30.5mm - is this correct? |
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