My SL175 look alike project.

[Richard Pitman]

I had a lot of parts left over, after I'd finished swapping things around on my CB and CL 175s.

I had a pair of wheels, an engine, a CB175K4 frame, seat, tank and side panels. Handlebars, controls, instruments, wiring loom, headlight. Rather than leave all these parts scattered around, I thought that I might as well assemble them.

All I needed was some forks, rear swing arm, shocks and fenders, plus a few brackets. And a can of silver paint.

 

[Richard Pitman]

And then my good intentions went out the window. First off, I decided that the boxy K4 tank looked wrong, so I got an SL175 tank and 'persuaded' it to fit. Part finished build ended up like this. Didn't look quite right to me, proportions all wrong.

 

[Richard Pitman]

So an SL175 frame was purchased and powder coated in a nice silver metallic finish, same stuff used on car wheels. Also needed to purchase a few more brackets and a battery box.

 

[Richard Pitman]

And this is it at present. Since the last photo, I've fitted a new chain and had a brief ride, seems very lively.

It has CD250U forks, a CB175 front brake and electric start engine. Home made 2-1 exhaust, air filters, seat and side panels

 

[J-T]

Very nice. Looks like a fun ride.

 

[Richard Pitman]

Resorting to typing this using Wordpad, as this site can't keep up with my typing speed.


I've just taken the SL175 out for a brief test ride. It went well, with a few teething problems. First off, the gear change pedal position. I set it the same as on my CL and CB, but had problems changing gear. The SL footpegs are lower in relation to the engine than on the other two bikes, so I've rotated the gear lever down a few splines to a better position, hope that sorts it.


Halfway through the ride, the bike stopped, showing all the signs of fuel starvation. Big hiss when filler cap removed, so fairly obvious what that problem is. Bike restarted and got me home OK.


Awful resonance at around 7k rpm, either the exhaust or my home brewed alloy side panels, I've removed those for next test.
And finally, engine idling at 5k rpm when I got home. Wound the throttle stops out completely, no effect. Checked that slides were the right way round, checked for air leaks etc. Finally twigged that I just needed a bit more free play in the throttle cable, doh ....


On the plus side, bike goes well, seems quicker to 60 than the other two. It's running CL gearing, rather than the even lower SL ratio. Riding position is nice, my home made seat is very comfy. Exhaust is a touch too loud, wondering if an old school Honda baffle tube in the tail pipe might work. Brakes are fine, disregard my earlier concerns about the front unit.

 

[Richard Pitman]

I liberated my pair of pattern CB175 down pipes from this project to fit them to my CL175.

As I now had my cerakoted CL175 headers lying around, I just wondered if they'd fit the SL175 alike. And they do, although very tight against the left front frame downtube. Exhaust clamp does fully tighten down, so just relieving the pipe slightly would make it fit nicely.

I think they look trick !

 

[LongDistanceRider]

That looks like a winner to me.

 

[ancientdad]

Yep, really close to the frame tube but otherwise actually looks cool. And you have a convenient bracket on the frame right where a muffler will go.

 

[Richard Pitman]

A bit more fiddling with the SL175 alike. As it has CB175 switchgear fitted, with a turn signal switch, I decided to fit my spare set of proper Honda indicators. Tidies up the rear end, indicator stalk replaces bolt holding rear fender to frame, almost looks factory. No rubber mount though, so expect it'll get through incandescent lamps, LEDS might survive better.

On the front, CL175 rears, the CL175 fronts having been moved to the rear.

I gave up on the CL175 pipes idea, pipes ran much too close to left hand airfilter. I'll have to build a new SL style system, as my original tail pipe occupies same space as left rear turn signal.

 

[Richard Pitman]

Cut down K4 filters with replacement Ramair foam, fit neatly under side panels.

 

[Richard Pitman]

A used pair of 175 downpipes arrived this afternoon, so I can get on rebuilding the exhaust soon.

In the meantime I've been playing with those cheap pit bike carbs that Graham pointed out.

I've swapped the carb tops over, these needed few strokes with a file to get them to sit nicely. The choke mechanism was a direct swap, once I'd figured out that retaining nut was locked by staking over the end of the threaded shaft. The nut came off easily, but the end of the shaft needed to be filed before it could withdrawn from the choke mechanism. The clone carbs simply used thread lock, easily sorted with the heat gun.

The floats are interchangeable with each other. Float valve seat is fixed in the clone carb, but the needle appears dimensionally the same as the Keihin one, but with a viton tip, might be cheap source of spare parts.

Just a shame that the carb throat is so small. That said, the single cylinder bikes that this carb is intended for can rev quite high, so maybe it won't be as restrictive as I fear.

 

[Richard Pitman]

Just browsing through Zeke's old thread on dotheton site, and found this picture of an SL175 race bike, sporting a CL exhaust, shows the same tight fit that I found. Wish there was a picture of the left hand side of the bike, interested to see how the pipe fitted on that side.

Also note extra frame tube welded in, bracing the swing arm pivot. I do really like the SL frame, looks so neat.

 

[Richard Pitman]

I'm getting on with building my exhaust. The pipes were aftermarket CD175, 32mm external diameter, so I had to tack weld some 35mm OD sleeves onto them to match the 2-1 section that I'd previously built.

 

[911hillclimber]

I think you possessed!

Carbs look good, for the moment I've abandoned mine until later. Hope you persevere.
The SL frame really is a frame and so much neater than the CB frame.
Look forward to seeing you resolve the Snag List.
Graham.

 

[Richard Pitman]

Obsessed, certainly ...

 

[Richard Pitman]

Got the exhaust welded up and test fitted.

Welds courtesy of local pigeons.

Although ugly, they are strong, as I found when I had to remove and reposition the mounting brackets

And a bit of black high temp paint covers a multitude of bodges ….

 

[Richard Pitman]

Fitted to the bike. Just need to have a go at making up a heatshield now.

 

[ancientdad]

Looking very much as it should now Richard, and the heat shield will top it off.

 

[Middletons]

Nice work!

 

[Number13]

Looking good Richard. I'm sure I'm not alone in wishing I could hear it too.

 

[Richard Pitman]

I have had it running previously, and it really just sounded like a rather loud CL175. I may insert a baffle in the tail pipe, although that Triumph silencer has all its internals present and correct, just the catalyst removed.

Battery has been removed for the winter now, and I need to get into the carbs again, CB200 carbs currently fitted, with the 88 mains etc. ( and UK spec full size ventur1 !)

 

[Richard Pitman]

First attempt at a heatshield, in stainless steel.

Easy enough to drill and cut, not so easy to get the curve bent by hand.

 

[Number13]

Yes difficult if you're not used to working metal in that way. Sam Lovegrove springs to mind, I bet he could make short work of it but mates like that are thin on the ground. In a similar position I would be tempted to have it reversed on a thick pad and get the ol cricket bat mallet tapping.

 

[66Sprint]

Three inch PVC sectioned lengthwise, one half is clamped between vise jaws on the long edges.......Set the blank on top, bridging the sides....
Two inch steel pipe pulled down (through) the blank into that "hollow trough by tightening several "radiator" hose clamps along the length semi-evenly....
Vise prevents PVC from splaying open too far, and blank gets curved approximating the inside arc of the 3" pipe.......

 

[Richard Pitman]

Thanks for the suggestions and advice.

In the end, I simply bolted it in place and used my rubber hammer to contour it.

I'm now a bit concerned about silencer to swing arm clearance. I can bounce on the seat without conflicts, but can't fully compress the suspension. I'll remove the right hand shock and try again another day, too cold out there this afternoon. Nothing that a big hammer can't fix ...

 

[66Sprint]

Looks fine....You might get away with just spacers between the muffler mount tabs and the frame...It doesn't look like it needs to move much....

 

[Richard Pitman]

Wincycles (Oemstd) carbs just arrived. Ordered on 11th Jan, arrived 23 Jan, quicker than expected, and NO extra Customs charges either, which was nice. I fully expected having to trudge up to the sorting office to collect them, but they just arrived with the normal post.

A cursory inspection shows them to appear to be close copies of the right hand side Keihin. Threads on the carb tops are a bit rough, slides are tight in their bores. I've inspected the main and idle jets using my jewellers loupe, and can see no markings indicating jet sizes, but they appear interchangeable with the Keihin parts. Floats are plastic, and the needle valves are tethered to the float arm, which is a useful improvement.

I'm afraid it's just too cold to be messing around in the garage at the moment, so testing will have to wait, that and lockdown as well. Actually thinking about doing a PC build, must be almost10 years since the last one. Time to go back to AMD I think...

 

[911hillclimber]

Been waiting for this Richard.
not a bad start, some needle file and polishing then.
Can you translate the last sentence please!
G.

 

[ancientdad]

Been waiting for this Richard.
not a bad start, some needle file and polishing then.
Can you translate the last sentence please!
G.

Apparently he's thinking about building a new computer for himself and may go to an AMD processor/motherboard instead of Intel this time. Ten years time is a lot of change on both Intel and AMD's products. Personally, I left AMD behind a long time ago and have been very happy with Intel for the last 10+ years. My E5-1620 4 core Xeon processor (10 Mb L3 cache) Dell Precision Workstation desktop is more than fast enough and multitasks like crazy, plus the boot time is excellent. Of course, I'm still running Win7 as I absolutely hate 10 (and MS for that matter)

Not a highjack, Richard brought it up...

 

[Richard Pitman]

I used to be a computer nerd until I got back into bikes some 20+ years ago, then I rather lost interest. Back then, an Intel 80386 was a big deal, after that I started using AMD stuff, Athlons etc. And then Intel got their act together with the I5, I7 series, so I went back to them, and built this I5 box, upgraded over the years, currently Win10, 16gb, 1tb SSD, networked to a Synology NAS box.

I'm now looking at the Ryzen5 CPU, seems to be in the price vs performance sweet spot.

 

[Middletons]

Wincycles (Oemstd) carbs just arrived. Ordered on 11th Jan, arrived 23 Jan, quicker than expected, and NO extra Customs charges either, which was nice. I fully expected having to trudge up to the sorting office to collect them, but they just arrived with the normal post.

A cursory inspection shows them to appear to be close copies of the right hand side Keihin. Threads on the carb tops are a bit rough, slides are tight in their bores. I've inspected the main and idle jets using my jewellers loupe, and can see no markings indicating jet sizes, but they appear interchangeable with the Keihin parts. Floats are plastic, and the needle valves are tethered to the float arm, which is a useful improvement.

In the set I have currently, the idle jets are different in length than stock. I have never seen markings on the jets of these carbs.

 

[911hillclimber]

Can the original jets be simply transferred across?
the real benefit to me would be the clear passages of the bodies.

 

[Richard Pitman]

Yes, the jets are a straight swap and the actual body castings appear pretty much identical. Here's a set of photos, should be self explanatory. Ignore the non standard choke lever on the Keihin carb.

 

[Middletons]

The jets will physically fit in either carb, but as I noted earlier, and as pictured above, the idle jets are different in length. That has to effect performance.

 

[Richard Pitman]

The jets will physically fit in either carb, but as I noted earlier, and as pictured above, the idle jets are different in length. That has to effect performance.

Hmmm, I wonder. The fuel level must be the same in either carb, given the position of the main jets, so the extended lower portion of the Wincycles idle jet doesn't actually serve any purpose, unless the fuel level was too low. The business end of the idle jets are similar.

 

[Middletons]

the depth of a jet in the fuel is a determining factor of mixture. those two jets should theoretically produce different air/fuel mixes.

 

[66Sprint]

NO....Where the fuel level rises to and the distance it has to be drawn up from there (that level) to enter the inlet tract do matter, depth below liquid surface is not relevant to any great extent unless it's shallow enough to expose the bottom end to air instead of fuel .....

Think height of and above fuel in jet tube rather than total depth of tube in fuel
A straw will deliver drink whether it's only half way in the fluid or all the way near the bottom of the glass......

 

[Middletons]

I see. thanks for the correction and clarification.

 

[911hillclimber]

Good to see them in detail Richard, thanks for the post.

Waiting on a gasket set for mine before I can get to mess with the stock carbs, but I think I know where I will be heading..

 

[Richard Pitman]

As in the other thread, I've fitted the Wincycles carbs to my CL175 to test them.

Meanwhile, I've been modifying a CB175 K4 side panel to fit my SL175. I managed to find a left hand SL panel locally, but the only right panel is in the US, and too expensive to justify importing it.

Two of the CB locating pegs cut off, reattached with KB Weld and aluminium reinforcement. I also had to sand down the raised section where the CB175 badge went, built up behind this area with filler.

K0 replica SL badge applied.

This is a real SL175 K1

And this is my look alike version.

 

[Richard Pitman]

I changed the carbs the other day, swapped the CB200 items for the freshly cleaned carbs I'd just taken off my CL175. Fitted the battery from winter storage, and tried to start it.

No go. On inspection, both float bowls dry. Turned out to be the fuel tap filter, tank obviously not as clean as I thought. With fuel flowing again, it starts and runs. Clouds of smoke as the exhaust paint cures.

Spitting back through the carbs. No obvious air leaks, and it did same with other carbs, so I'm going to check the ignition timing, and check the advance mechanism. Or maybe it just doesn't like my home made 2-1 exhaust.

 

[robbnc]

Nice job Richard. I’ve got a set of Oemstd carbs coming for my SL. Are they set up pretty well and ready to run right out of the box?

 

[Richard Pitman]

It'll be interesting to see !

They sell the same set of carbs for the CB, CL and SL 175s, while Honda had different jets for each variant.

On my CL, I just fitted them and they worked straight out of the box. My CL has David Silvers pattern CB175/200 exhausts, and CB200 air filters, rebuilt with RamAir foam, so it's different again from the three specs just mentioned.

Chances are you'll be fine. At least we don't need to mess setting float heights …..

 

[Richard Pitman]

Did a little bit of work on the SL alike yesterday afternoon. Fitted some inline fuel filters to replace the clogged gauze in the fuel tap. Used some Gorilla glue inside the throttle side handle bar grip to stop it slipping on the nylon throttle tube.

Modified a baffle from a Chinese pitbike exhaust, basically drilled a few more holes in it and welded a nut onto it, to make a mute to fit in the tail pipe of my home brew exhaust. Seems to work OK, takes the edge of the bark, bit more neighbour friendly. Engine now starts ( on the electric start ! ) well and runs OK, but still spitting back, so ignition check is next on the list. I've got a CL360 stator fitted, no timing marks, will need to check that out.

 

[Richard Pitman]

As above, a CL360 stator with a CB200 rotor on a CB175 engine in an SL175 frame.

I added the timing mark pointer myself, need to check that spark really is happening at the right time !

EDIT On reflection, that's a 175 rotor ( 307 ), CB200 (354) rotor is in my CL175 engine.

 

[ancientdad]

It must be hard to keep track on the SL175 alike Richard, you should document the mixed bag of parts for future purposes (or then again, simply refer back to here I guess). I assume the 360 stator creates more output?

 

[Richard Pitman]

We are back to idle hands again. The 175 stator makes 90 watts at 5k rpm, the CL360 one makes 110 watts, so not much in it really.

That said, it might be easier to find the later part. Also, with an electric start, the little battery on the SL needs all the help it can get, efficient and cheap Chinese pit bike reg rec also helps out.

 

[Richard Pitman]

My idle hands strike again.

I've got a genuine K1 seat on the way, so while I'm waiting I decided to experiment with some other parts. I'd already had a go at making my own seat, and the actual metal base that I made worked well, using the stock hinges on the frame and an original latch.

I also had a crappy plastic based 'café racer' seat, which I'd initially dismissed as rubbish. However, bolted to my cut down home made steel seat pan actually forms quite stable seat. I also sprayed the Honda logo, using a stencil and silver vinyl dye/paint.

I shan't keep it like this, but it does illustrate how one of those cheap Ebay seats could be made to work with the stock hardware, rather than just bolting it direct to the frame with random brackets and roofing bolts …

 

[Richard Pitman]

Adrian kindly delivered a genuine K1 SL175 seat on Monday, so I got busy fabricating a seat hinge to fit it. I already had the correct seat latch.

Bike looks so much better with the proper parts.