First build on my Fuji 10-speed

I don't think you will find a wider tire for your 27 inch wheels. Mountain bike wheels, 26x1.5 or so, will normally fit a frame designed for 27" tires. You will probably need to swap your brakes for some bmx brakes. See if you can borrow some mountain bike wheels from a friend to make sue they will fit.
The vibration is probably the result of your frame. High quality frame tubing, like Reynolds 531 or Tange 4120 transmit more engine vibration than cheaper tensile steel.

You can take a big Crescent wrench to the idler bracket and bend it enough so that your idler pulley is inline with the sprockets.

Good luck with your project!!

The four stoke engine will usually fit beach cruisers that have only one top tube. Cruisers with an upper and lower top tube provide less room. Steel mountain bikes with a horizontal top tube (not a sloping top tube) provide a lot of engine room.
I noticed you still have a road bike seat on the Fuji. Replacing it with a sprung cruiser seat may help with the vibration. Thicker foam grips on the bars may also help. It could be worth a try before swapping frames.
There are no absolute answers to our motorbike issues. Just pick the solution that it within your abilities and budget.

Edge said:

The tires say 27 x 1 1/8 hooked rim. Couldn't I just go with 27 x 1 3/8 tire and tube on the same rim? Would the extra 1/4 width ride better?

http://www.amazon.com/Kenda-Street-...id=1370794984&sr=1-1&keywords=27+x+1+3/8+tire

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Your present tires are about the thinnest you could have on those rims- although there are 1 inch out there- hard to find and expensive

Yes, the the 27 x 1 3/8 are then the widest (that's my bike in the customer images on Amazon) and those tires also give a little taller profile- for $14 shipped , they are a pretty good deal.
The change from 1/8 to 3/8 will give you a smoother ride and give the rim a bit more protection-

someone mentioned switching to 26" wheels- if you really wanted to switch- 700 c would be more compatible, and then you could wider on the tires still,
although the 27x 1 3/8 size above is already roughly the width of 700 x 38mm,
and 700 width descriptions vary a bit between manufacturers like pairs of pants.
You may or may not be able to use the same brakes then-
going to a longer reach on vintage 27 bikes is difficult because the brakes are already at the longest reach and then you have to get something much clunkier

I'd probably try the 27 x 1 3/8 gumwalls- they'll handle the weight much better- 1 1/8 is too thin, though i might cheat one on the front if I was really wanting a light two stroke build- I usually use 1 1/4 and currently have tha on those wheels now. But the china girls are lighter.

a 4 stroke on a roadbike is tough- how do you peddle that?

Just keep at it; ways to fix issues will come to you.

You should try running the chain without the tension pulley. If you keep it try moving it farther from the wheel sprocket.

kevyleven007 said:

You should try running the chain without the tension pulley. If you keep it try moving it farther from the wheel sprocket.

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NOT going to work- look at the photo from above- the chain is already practically parallel to the chain stay- almost always gotta use a tensioner on a vintage diamond frame I think- that's why I've never built one, though sorta planned a couple I scrapped- I stay with cruiser frames now- mostly for chain clearance- and the tank in the way thing-

I was just going to try one with this tank-
http://www.ebay.com/itm/37014959811...X:IT&_trksid=p3984.m1439.l2649#ht_1852wt_1018
and hang it under the top bar, ast the seat tube


but same chainstay problem- an I just don't like tensioners!
the new ones really aren't that heavy, but I'd like a lighter frame

I motorized an old 10 speed road bike. Used a guru bee 66cc engine. I just got rid of my chain tensioner. I have just enough clearance for the chain. You can check my profile for pics.