converting from two stroke to four, questions

C

cobrafreak

New Member
My 2 stroke engine seized after 1250 miles. Not too bad for a two stroke I guess. That works out to .10 cents a mile. I pushed the button and ordered a complete four stroke kit. Not the 4G belt drive one but the grubee with the gearbox with the 3 big gears inside. I don't have it yet, it will probably be delivered in a week and a half. Bear with my stupid questions as I am new to four stroke:

1. Can I use the same 415 chain size from the 2 stroke engine?

2. I've seen others do this but want to ask anyway, can I remove the forced cooling shroud as it is a moving vehicle. Not the sexist thing around with the shroud on.

3. The ad for the grubee 4 stroke kit says the gearbox has a "wet run option". Does that mean it is possible to seal the gearbox to run with oil? If so, what needs to be done to do this?

4. I really like pedal start like my two stroke had. Is it possible to make the 4 stroke engine pedal start? If not what would need to be done to accomplish this? I would like to do this to delete the pull start lever for a cleaner look.

5. Any worthwhile upgrades or mods for the 4 stroke kit for more functionality, performance, or longevity?


Thanks ahead of time for the help people!
 
Yes you can use the 415 chain, most builders do unless they are using the 4-stroke shift kit.

Yes you can remove the cooling fan shroud. I ran a series of tests monitoring the head and engine temp with a had held Laser Thermometer last summer on my Honda motor removing the various pieces of tin and finally the shroud and saw no increase in temperature readings. I did put the shroud back on though due tho the fact that the cooling vanes on the flywheel were shredding the cuffs of my jeans.

The Grubee III is supposed to be able too be run wet, but it seems the few people who have tried it have been less than satisfied with the results. There is a very narrow thin gasket that seals the gearbox base to motor mounting surface and there is another gasket that seals the two halves of the gearbox. Excessive clutch slipping seems to be the problem reported when running the gearbox wet? The newer style clutch is supposed to have addressed this problem, but I cannot say from personal experience that it has? When my Type III gearbox started chewing itself to death after 6000+ miles I switched to the 4G for Honda Drive Unit.

As for pedal starting? I'm sure it could be done by fixing the clutch bell to the clutch shoes and then using the engager system on the gearbox as/like a clutch? But the engager as designed is very problematic in this gearbox and you will have a better riding experience if you set it up so it is permanently engaged. Using it as a clutch at any rpm above idle usually meets with catastrophic failure. If you really want to have pedal start you should contact Mike Simpson of Simpson Motorbikes in Sacramento and see if he can sell you one of the original EZ MotorBike Silent Drive Reduction units. These units were essentially a slipper clutch set-up using a v-belt and pulleys and I believe could be pedal started.

The one thig I would highly recommend that you do when you and if you decide to use the Grubee III gearbox is if it comes with the newer style clutch (the one that uses compression springs/coil springs) be sure that they have a spring rate of approx 60lbs./in. The stock springs used to be 40lbs./in springs and the clutch was fully engaged at idle with these springs.

ocscully
 
I HIGHLY advise you NOT to use the engager on the Stage 3 as a clutch. It will NOT last and can only be used reliably while the engine is at idle.
 
Cobra - I have been using one of the clone engines with the hoot gearbox for over a year. I just sold the bike and the new owner loves it. I took all the shrouds off, you do need something to keep it from sucking your trousers. I took all the permanent grease covers off the bearings in the box, aligned the gears at the end of the clutch and filled it with hydraulic oil, seems to work fine. I would like to see a clutch like the 2 stroke made. if it had a cog drive around the outside and a mounting for the bearings and clutch lifting it could be made to work like one of the new generation drives, another idea would be to use the clutch off of a Honda C100 from the 60's it is a push pull clutch, and I know it would work dry. I have a bunch in my garage and I have looked into it for quite a while. The CVT has a lot of drag and is fairly bulky keep us posted. Have fun with the new build.

PS: The Honda clutch can also be pushed in from the outside to work like a normal clutch.
 
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