Dual Chain Transmission Won't Fit

phil4989

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We just got in a bikeberry dual chain transmission (link below) for my son's build. Now before you all tell me to return it and get a belt drive (which I may do), hear me out. My son is on a limited budget, thus the more inexpensive parts. We tried to install it on an engine that we got off amazon (link below) that I thought would be compatible. The engine said 142F and has a tapered shaft. When we installed the transmission, it wouldn't fit. The nut and bolt holding on the bell seems to stick out too far and touches the clutch, making the transmission not seat correctly on the engine.

Anyone else have this problem or know of a solution other that returning the transmission?

Transmission Link: https://www.bikeberry.com/4-stroke-transmission.html
Engine Link: https://www.amazon.com/gp/product/B06WRQRTH4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Due to Covid and shipping incompetence, the bikeberry transmission took a month to get here. So doing a return and ordering a belt drive is not our first choice.
 
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When we started, we had on a 44t rear sprocket. At the time we didn't realize it was not for hilly areas (NC), and he burned up several clutches. This also made the transmission a bit off balance and you could hear it rubbing inside. Sounds like the bell shaft me be slightly bent. We are currently putting the old one back on until we figure out what we are going to do with the new dual chain. I have read the one it came with is pretty bad and will fail quickly. He also wanted to upgrade, so the transmission seemed like an obvious choice.
 
Did you pull the transmission off the side of the engine, 4 little bolts and fit the BB trans on there?
 
With the information supplied, your final gear ratio seems too high. What's the transmission's gear ratio? You can tell by opening the cover and counting the sprockets' teeth.
How many teeth does the outer sprocket have? What type of rear sprocket do you have? #35?
 
Chainlube: yes, we pulled the transmission off the side and put the BB one on there, but when the bolts are tightened down there is still another 1/8 inch to go before the transmission mates properly with the engine. All because of the center bolt in the BB transmission. I measured the depth of the bell on the new transmission, it is definitely more shallow.
 
5-7Heaven: We were going for a low gear ratio. There are a lot hills around here, several have stop signs right in the middle. He would pedal assist from a stop, but it still wasn't enough. The clutch kept wouldn't fully engage due to the high torque and low RPM. The other benefit to a low gear ratio is his top speed is lowered at bit, which makes my wife feel better about him riding it. :)
 
@Don_Parsons He's talking about a centrifugal clutch inside of a "transmission" (reduction box) on a four stroke. Different yet somewhat similar to what is built into the 2 strokes. You can get centrifugal clutches for the 66cc if you don't want to have to use a clutch lever and make it auto engage but it would limit your bottom speed unlike the pressure plate and pads manual clutch that is in them stock. (I personally prefer the manual all day)
 
Good catch Frogslayer. I forgot to mention that I was referring to a centrifugal clutch and that it was really a reduction box not a true transmission. I noticed everyone was calling it a transmission, so I jumped on the bandwagon.
 
It's fine im not the word police lol. You can call it what ever you like. I feel like I've read about this exact scenario before. Have you tried searching the forums extensively? I know some stuff gets buried in off topic threads and is really hard and time consuming to find. If i can remember correctly i think the previous guy used washers as spacers between the covers to get it to mount at the right depth, which is just barely not rubbing I'd guess.
 
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