1970 CL100 Cafe Project - Bore Information?

10459 Views 31 Replies 10 Participants Last post by monkey, Mar 1, 2015

CNorthness

Discussion Starter · Feb 27, 2015

Yo! Sorry if this is a subject that's been covered already. I'm new to the forum and couldn't seem to find anything. So! I bought a 1970 CL100 back in July from the second owner, who bought it back in 1973. He used it sparingly, but maintained it well until about five years ago,. It has sat since then. I stripped the bike to a motor and a frame, and all seems straight forward thus far except for the motor. Given the scooter-esque displacement, I'd like to add a little more get up and go, while simultaneously getting rid of any compression problems that may or may not be present. So, hey! Let's just bore it, right? BUT... I have no idea what the best compromise between sustained reliability and performance may be... I've heard of people boring the cylinder to fit a 750 sleeve and piston, and that it's extremely reliable, the only difference being that the 750 piston requires a 15mm wrist pin rather than the 14mm in the 100. That can be reamed, correct?

But is that even the best option? What would be the displacement, horsepower, and performance gains on this? Would anyone happen to have firsthand experience with doing such a modification on this bike? Any and all performance/reliability tips would also be greatly appreciated.

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Witworth

· #21 · Feb 27, 2015

Buy a Skyteam ACE 125 tank and seat.

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I think the only thing you will learn is bikes cost real money, and hotting up a bike is beyond you meagre skills.

Danger, is my business."

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CNorthness

Discussion Starter · #22 · Feb 27, 2015

That's exactly the point. I won't learn unless I try this sort of thing. I bought the bike for next to nothing and have plenty of room to lose out. I'm paying for the learning experience. Whatever time and money I throw at this will be for learning's sake. Thank you for all the technical support. I believe a 125 from the same era uses the same mounts and all, correct? Just as an afterthought for an option B, given I muck this up horribly.

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CNorthness

Discussion Starter · #23 · Feb 27, 2015

But! As far as style, I don't know if this is cafe sacrilege, but I plan on fabricating a hoop for the rear of the bike and welding it on to replace the forked back end, then building myself a long, flat brat seat.

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Witworth

· #24 · Feb 27, 2015

CNorthness said:
But! As far as style, I don't know if this is cafe sacrilege, but I plan on fabricating a hoop for the rear of the bike and welding it on to replace the forked back end, then building myself a long, flat brat seat.

Well you don't need a long flat brat seat on a bike that puts out about 9 BHP.

Unless you plan on having a relationship with a blow up woman... Who you gonna haul?

Danger, is my business."

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Witworth

· #25 · Feb 27, 2015

CNorthness said:
That's exactly the point. I won't learn unless I try this sort of thing. I bought the bike for next to nothing and have plenty of room to lose out. I'm paying for the learning experience. Whatever time and money I throw at this will be for learning's sake. Thank you for all the technical support. I believe a 125 from the same era uses the same mounts and all, correct? Just as an afterthought for an option B, given I muck this up horribly.

The 125 motor fits straight in.

Danger, is my business."

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jaguar

· #26 · Feb 28, 2015

There is no cafe racer style.
you are talking about choppers.

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kerosene

· #27 · Feb 28, 2015

The best hot options are:
XL185 (actually 180cc) or XR200 (actually 190cc) crank and the cylinder+head from either. The cases need machining which means splitting. Its not a huge deal as its a simple bike. They can be further bored to true 200cc or even over. I think the 190 would be plenty.
Then get roller bearing cam (webcamshaft I think) and titanium valvetrain components. You naturally need the camchain with tensioner from XL185/xr200. Naturally carb (there is a mikuni pumper version of the 28 that might work perfectly with a hot engine. Naturally after proper tuning). Oh and the newer heads are for CDI ignition, not points so there is that. The stators are different. othrwise you could use cb360 stator to go 12V with better output but the CDI is an issue. Maybe you'll just design a transistor system of your own...

So it all can be done. And you will get 18+ hp, maybe even 20+ if everything is done well and right. It will cost you maybe $1000-$1500. That right there is your answer. If you are not doing it because of the tinkering and challenge itself its absolutely pointless. No sense at all.

You could fit a full (early) xr200 motor (do they have light coil, not sure) or chinese pushrod honda knockoff engine. Its still a lot of work for questionable goal.

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kerosene

· #28 · Feb 28, 2015

CNorthness said:
That's exactly the point. I won't learn unless I try this sort of thing. I bought the bike for next to nothing and have plenty of room to lose out. I'm paying for the learning experience. Whatever time and money I throw at this will be for learning's sake. Thank you for all the technical support. I believe a 125 from the same era uses the same mounts and all, correct? Just as an afterthought for an option B, given I muck this up horribly.

you are failing in the 1st lesson my man. I mean this kindly. You are failing to hear what people are saying. Get the bike working as well sock 1st is the smartest thing to do. If that is not enough after a few hundred miles (you will notice that the suspension and frame are also scooteresque) sell it (if you kept it stock, its worth decent money well sorted out) and buy something else.

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jaguar

· #29 · Feb 28, 2015

I own, and have owned a few of these Honda singles.
Been down the "make it less slow" and all that before. Personally I now just prefer them stock. I view them as best in this role.
BUT completely understand the desire to learn and just generally make something out of random parts. In that respect these bikes are great for that.
They are small, parts are easy to get and cheap. Honda made millions of these things. I would rather see someone learn to mix and match junk on one of these then blow apart a 4 cylinder and drown.
The idea should always be fun.

But dont brush off what people are saying by using the cop out " ill learn it myself". If that was the case then you would not be on the internet seeking out help, you would be in the garage doing something. So take some advice and you will have a leg up.

That motor that kerosene was talking about might be something fun for you to build.
What I would do is service the shit out of the bike you have and ride the wheels off it. While doing that find a spare motor and build it up.
You will then be wrenching on a fun project AND riding the bike. Then one weekend swap the motors. Another thing you gain with this is a good baseline.
the 18hp of the new motor will still feel slow, unless you have been riding around for a while with 11hp.....

And we do still need to talk about how bad these bikes are at "cafe racer" builds.
The motors HATE to run with short pipes or pods. Rearsets are hard to mount. ect ect
Play to a bikes strengths. "racing" aint it.

Here is mine

Bought it with 1100 miles from the original owner's family. I use it to run out for beer (that rack is epic), pick up parts and just general running around.
It is a blast. Have run it out on the beach, and taken it though the woods. Just a nice bike to have around.

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CNorthness

Discussion Starter · #30 · Mar 1, 2015

Thanks, Jaguar. Likely the best post on the thread thus far. Over the last few days I think I've come to the same conclusion. I'm going to inspect the cylinder walls for any damage, and if all is well, put it back together and build something to swap. Yes, everyone: Build another gutless motor to make less-slow (very well said, Jaguar). Again, money can buy a racer or a buildable platform. But this is all for knowledge.

Brat seat because I think they look bad ass.

I'm not raking any forks or trying to find any chrome, chainlink ape hangers; So nah. Not choppers.

But! I'm fond of the hot motor described by kerosene. Any other useful technical suggestions?

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Witworth

· #31 · Mar 1, 2015

CNorthness said:
Any other useful technical suggestions?

CC's sonny.

Danger, is my business.

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monkey

· #32 · Mar 1, 2015

I would leave it stock... beer runs forever!!!! Brat seat? whatever that is

The big old cushy cushion is a must for the ladies!!!

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