1970 Honda CL175, street tracker brat type of thing

sancho

Active Member
Hello everyone! This is kinda after project actually because I'm already done with the bike but I thought I would post it anyway. I've been a long time lurker of this forum and learned a great deal! Absolutely amazing people on here, very helpful and knowledgeable. I pretty much didn't need to ask any questions or start new threads, I mean every question or problem I had, I would search on here and find the solution right away through reading other people's posts. The forum is a goldmine for newbies like me.

Recently bought a 1970 Honda CL175 for dirt cheap from a guy who has a shop in baltimore and was going to restore it for his daughter but she lost interest. Wasn't running but ran the season before (of course). This was going to be a small in town city scrambler type of bike and I didn't have much cash to spend on it. Here it is the day I bought it:
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It was in alright shape, nothing some elbow grease and some tools couldn't take care of. So here were the bad:

- No title, last time it was registered was in 1985, it actually had the registration card from MD.
- Spark plug threads were stripped
- muffler had rust holes
- fork seals were shot
- rear shocks shot
- carbs clogged up
- some electrical issues
- throttle cable snapped
- clutch cable bad, clutch adjuster fixing piece broken
- rusted rims, i think it had some water in the tires for a while, the rust was only on one side of the rims
- clogged petcock
- rusted seat pan
- broken headlight
- rusted controls
...etc...etc, the usual old bike problems, but these were the majors

Started taking it apart and trying to get it started at least.
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Found out there was no battery tray.
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First order of business, cleaned out the carbs. I actually bought an ultra sonic cleaner from harbor freight. Worked pretty well but not nearly as good as I thought it would. Overall not worth the money.
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BTW I think these carbs came from a CB175 they were 21mm, and CL175 manual called for 22mm.

Next up were the stripped spark plug threads. I read a bunch of stuff about which kit to use and ended up with TIMECERT spark plug thread repair kit. Kinda expensive at about $130 but IMHO it is well worth it. I've used helicoil before a bunch of times and TIMECERT is way better I think, especially for something as important as spark plugs. The instructions were pretty simple. I was worried about small shavings getting into the cylinder, but I used some grease that caught most of it and then blew it out with a compressor. Seemed to work pretty well.
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Then I measured the compression of both cylinders, both came out to be 130-135psi. The manual called for 142psi as normal. So, I thought it was close enough and decided not to do the top end.
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BTW the compression test kit from Harbor Freight is terrible, I read a bunch of complaints about it. The hoses are too soft I think and kept reading 35psi, which scared the crap out of me initially but I went and bought craftsman compression test kit from sears and it worked fine. So stay away from HF test kits.

Anyway I got the bike started and it ran pretty good but still needed some fine tuning because it had no air filters and exhaust was leaking somewhere. But at least I knew it ran!

Bought a bunch of parts from DCC and continued to disassemble.
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Then I got the rear swing arm stretched about 2.5 inches. I didn't want a huge stretch but I felt like the bike overall was a little too short for me as far as the stance. So I thought a little stretch will make it look just right.

So here it is with the stretch
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And Here is the difference:
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I really like the fat tires, scrambler look. Did some research and reached a conclusion that I would need to put on wider rims in order to run wider tires. I decided to go with Dunlop k70 tires because I got a killer deal from a local parts guy. I ended up getting 18x4.00 rear and 19x.3.25 front tires. I knew the fat tires were going to rob some power, acceleration, and top speed. But again this was going to be my in-town cruiser to and from work in downtown traffic so I wasn't too worried about it.

So, I went with MikesXS rims, 2.15x18 rear, and 2.15x19 front. I was worried if they would fit the CL175 hub and spokes but they turned out fine. Here is the thread I started about it:

http://www.dotheton.com/forum/index.php?topic=46649.0

So here are the pics of the wheel build:
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I used dial gauge and a wheel stand from Harbor Freight to true the rims and it worked out great. The tolerances specified on the manual were pretty generous already but I ended up truing it even more. It took a looooong time to do this, definitely requires a lot of patience.

Cleaned up the frame next. Just used some steam cleaner and some degreaser to take off all intergalactic crud that was on there. I was very surprised how the original paint was still in good shape and decided not to spend any money on painting.
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Rebuilt the forks next. This was a bit of a challenge because of the stubborn old fork seals that were stuck in. I ended up using a method I read here, which was filling it with water then using a hydraulic jack stand pinning it under something to push the seals out. Worked like a charm! Debated whether I should use tranny fluid or fork fluid. Ended up using w15 modern fluid. Seems to work fine, except I hear a lot of slushing when the forks compress. Not sure if thats good or bad.
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Then I finally got a roller. Had to come up with something for the rear brake rod. Ended up making it from a piece of metal rod. Also mounted the tank to see what it would look like.
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Then I cut the rear fender up. Stripped all the paint off and clear coated it. Did the same thing to the gas tank. But decided to leave the paint around the honda badge, mainly because I was lazy but also cuz it kinda looked cool.
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Then I cut up my exhaust, muffler was in bad shape had rust inside it. Luckily the pipes were ok. I saw on here the DIY baffles someone had made. Thought that was awesome, so off I went to home depot and got some copper pipe. Made the baffles and tested them out. Actually sounded really good! Not sure about performance. Probably made it worse.
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I found some stock airfilters on ebay for cheap and decided to go that route because I current jetting seemed pretty close to stock. I think they worked out pretty well, it pulls nicely, and seems to work with the exhaust well. At least in my opinion. Painted and reconditioned small bits and pieces like headlight. Installed DCC turn signals. Used one of the old giant turn signals and turned them into a stop light. Had to gut the internals out and replace them with some generic stop light guts I got from Autozone for $10, worked perfectly. I will paint the lens with a red tint. Reassembled everything and here she is minus the seat:
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Experimented with this seat from biltwell but it just looked terrible and wasn't sure how I was going to mount it. Then ended up going with a biltwell sportster seat from lowbrow customs. It worked perfectly. I had to make a small tab to mount the front part to the frame, but the rear mounted on to the fender so it was easy.
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Oh and also, I had the hardest time finding this little guy! The damn exhaust crush gasket. Anywhere I looked I found copper ones that were supposedly replaced the previous part number but were too large. Ended up getting the right ones on ebay but they were not copper, more like fiberglass. After installing them the bike ran like clock work.
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And here she is as it sits right now!
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OH BTW I live in an apartment and did all this in my underground garage hehe. I ride it to work everyday, and its a blast in city traffic! Absolutely perfect for the city!
 
I really like this one and those baffles are genius. A few suggestions though I would mount that brake light higher for safety sake and I would put some kinda fender on the front, the time you get caught in the rain you'll wish you had one and maybe some longer shocks in the back. But nice bike otherwise.
 
At first I was like, "Ha! He's doing this in his apartment's underground parking." But at the end I was impressed. Goes to show what one can do with some motivation. 8)
 
Cool! Smart to use stock air filters, jetting for these smaller engines is very tricky. I might switch to stock air filters.

BTW, the exhaust gaskets you installed are not fiberglass, they're asbestos. Be careful with them.
 
misfitfiend said:
I really like this one and those baffles are genius. A few suggestions though I would mount that brake light higher for safety sake and I would put some kinda fender on the front, the time you get caught in the rain you'll wish you had one and maybe some longer shocks in the back. But nice bike otherwise.

hehe, I actually stole the idea from http://www.dotheton.com/forum/index.php?topic=40461.0 but thanks anyway man. Yeah I am actually trying to mount the brake light on the rear fender and mount my plate down by the axle. Just makes more sense. As for the front fender, already got wet once hehe, and in the process of stripping the paint off and mounting it. Thanks again!
 
flyswat2006 said:
At first I was like, "Ha! He's doing this in his apartment's underground parking." But at the end I was impressed. Goes to show what one can do with some motivation. 8)

Yeah its a little hard not having your own garage, I have to haul my tools up and down, can't leave it there, but I like tinkering so this will have to do until i get my own space. Hehe, thanks man!
 
mannydantyla said:
Cool! Smart to use stock air filters, jetting for these smaller engines is very tricky. I might switch to stock air filters.

BTW, the exhaust gaskets you installed are not fiberglass, they're asbestos. Be careful with them.

Oh wow asbestos huh? I had no idea. hmmm does that mean there will be some asbestos in the exhaust?

Yeah I read that people have a ton of trouble fine tuning these small engines with pod filters and jetting. So I just decided to stick with stock filters. They seem to run pretty good. Wish I had a proper exhaust too. Probably will try to come up with some sort of 2 to 1 exhaust, we'll see. But thanks man!
 
sancho said:
Oh wow asbestos huh? I had no idea. hmmm does that mean there will be some asbestos in the exhaust?

Yeah I read that people have a ton of trouble fine tuning these small engines with pod filters and jetting. So I just decided to stick with stock filters. They seem to run pretty good. Wish I had a proper exhaust too. Probably will try to come up with some sort of 2 to 1 exhaust, we'll see. But thanks man!

I had the same bike and built it similarly - just sold it a few months ago.

The baffle solution I found, which turned out super clean, was to get aircooled VW exhaust tips and knock the baffles out of them. They're the same ID and OD as the CL exhaust, so you can just tap them into the cut off CL exhaust. Looks super clean, and really dials down the sound + provides enough backpressure.
 
buzzword said:
I had the same bike and built it similarly - just sold it a few months ago.

The baffle solution I found, which turned out super clean, was to get aircooled VW exhaust tips and knock the baffles out of them. They're the same ID and OD as the CL exhaust, so you can just tap them into the cut off CL exhaust. Looks super clean, and really dials down the sound + provides enough backpressure.

Yeah, I've read that somewhere, might have been your post. Can you share some details? exactly where you got it..etc? thanks.

I wonder if the bike will perform better with decent backpressure. I have been wondering about coming up with a some sort of 2-1 pipe with a shorty muffler at the end.
 
Re: (exhaust/jetting/tuning) 1970 Honda CL175, street tracker brat type of thing

Hey everyone,

Not sure if I should post this on the engine section but anyway. I'm trying to figure out some tuning issues. I've got a feeling that the bike is not running at its best. I got the carbs dialed down as best I can, it purrs like a kitten at idle, revs up pretty good under load, but as for top speed and power its lagging, feels gutless and weak going up hills.

I mean I know its only a 175cc, but I hit 55mph in 5th gear and its damn near close to revving its head off. I get up to 60mph eventually, but the rpms are so high after riding about 20min, the engine gets really hot (pulled up to a light and the motor was steaming).

Also going up moderate hills I get about 25-30mph in 3rd with pretty high rpms. In general, just feels very underpowered and sluggish. Also, I bet the fat tires, 4.00 rear and 3.25 front, are not helping me go faster. (oh and I am 170lb).

I'm guessing the home made baffles might be restricting the exhaust.

Here is what I have done so far to the engine to make it perform better:

- adjusted the cam chain
- adjusted the valves to spec
- adjusted timing
- cleaned the carbs
- adjusted the float bowl to spec
- synched the carbs to a point where the throttle response is nice, sharp, and even
- dialed the air and idle screws to where it purrs nicely at idle
- installed stock air box filters, nice and tight clamps so no air leak there
- new exhaust crush gasket installed
- Main Jet is at 90
- Slow Jet is at 38
- Jet needle is set to the middle setting
- starts without a choke, rarely needs it
- compression was measured around 135psi both cylinders.

I tried to play around with the float bowl and jet needle setting but all it did was foul the plugs or too lean, no improvement in power.
I tried running without the baffles, just straight pipe, and it ran way worse, absolutely no power and loud as hell, extremely annoying.

So, my plan is to fit the 12" shorty mufflers from dcc with a reducer kit to fit the 35mm(1-3/8") OD pipes.
http://www.dimecitycycles.com/chrome-12-inch-shorty-muffler.html

Hopefully it will reduce the annoying loudness open up the pipes. I would also have to go up on the jets. But at this point will the stock air filter become a restriction? Will pod filters be better with open pipes and jetting up?

Here is the pic of the plugs after running for a few weeks:
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I also thought about changing the sprocket tooth ratio to get more top speed, but then the bike feels so underpowered, not sure if that will do any good.

Please chime in with your recommendations and suggestions. I really am clueless when it comes to tuning. Learning as I go here.

Thanks guys!
 
nearly cried when I say what you did to this bike...The orange CL175 was my 1st bike , although it nearly killed me in an accident...I would love to find a bike like this, down under so I could restore it .........enjoy anyway...Chris in OZ
 
Quick update:

So, the compression on my bike has been deteriorating down to 125psi. Also the top end started leaking oil and gradually the motor just became nasty. I decided to take the motor apart and rebuild it for the winter. Took the top end apart. Cylinder walls seem ok, no scoring or scratches.

Measured the cylinder bore and pistons. Here are the results:

Cylinder bore: 52.01-52.02 Manual calls for: 52.00 - 52.01 (recommends rebuild if 52.10)
Piston width: 51.60 Manual calls for: 51.55 - 51.60

I feel like I am just within spec. Is it worth it to go for a piston and ring kit? take it to a machinist to bore it out?

Or should I just go with stock ring set, clean everything, hone the cylinders and put it all back together?

I do plan on servicing the head, cleaning everything, all ports, cleaning and lapping valves, replacing the springs...etc.

Hopefully this should bring my compression back up.

Your thoughts and recommendations are appreciated!

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