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January 27, 2007

Drive chain comes off at the start of run

At the Experiencing Drive held on December 16, 2006, it was found that the chain comes off from the driven sprocket at the start.
Root causes identified are as follows.
(1) While an upper portion of the chain loop becomes in tense, the other side (lower portion) becomes in loose. The loosened chain comes into the driven sprocket and the chain comes off finally.

Chain tensioner fabrication

I thought a tensioner is necessary to solve the problem, and started to make it.

I started to make a roller.
I got a piece of urethane pipe (external dia. 50mm, internal dia. 16mm), cut it into piece, and got the both sides recessed to install bearings that I have had.

February 17, 2007

Bracket became ready and I put the roller in place preliminarily.
I am going to put the assembly installed on the buggy and make a tensioning mechanism to keep the roller pulled upward.

April 22, 2007

Chain tensioner installation, adjustment, and trial run

I put the tensioner in place.
The concept is to maintain the tension by keeping the wheel pulled upward, using a rod and spring.
Upon this, the problem at the time of acceleration was solved that the lower portion of the chain loop became loosened and the chain itself came off from the driven sprocket.

Nevertheless, another problem still remains that the upper portion of the chain loop becomes loosened and jams around the drive sprocket when deceleration.
Even lately, I just noticed that a plastic cover and a metal guiding component around the drive sprocket became significantly failed and one of the fixation holes at the engine side also became failed. This may be because of the excess looseness of the chain happened before.

The only solution of this type problem would be to keep the tension of the chain monitored and adjusted.
Tensioner may have to treated only as a supplementary measure.
Another thing I remember and felt that I have to keep in mind is that the instruction of the "non-sealed" drive chain says "Use for motorcycle only up to 125cc", as well as a fact that the weight of the buggy is indeed more than the weight of a representative 125cc motorcycle.

May 3, 2007

Re-adjustment of chain tensioner & trial run

At the last run, the practice learned was that I have to keep the chain cleaned and lubricated every after run.
The chain, shown in the photo taken only after 20 to 30 circulations of run, convinced me the importance.
I also put a slider made by a piece of rubber to make the chain not to interfere with the frame structure.
It looks that the slider does not become significantly worn if the chain is kept properly lubricated. Things look fine for now.

The guy driving is M. Yoshimi, a friend of mine, who drives more aggressive than ever.

All things about chain and the tensioner adjustment have been done.

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