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Discussion Starter · #1 ·
hi all,



just recently i brought a XR50 and have found a cheap CT110 postie. I want to put the 110 motor into the fiddy for abit more GO!!!!



common cents i know;



1) 110 cylinder is longer so exhaust has 2 be modded (or brackets)

2) Have to gear it propely.



can anyone bring asny other problems up???

What gearing should it run???

Would i use the stock xr engine mounts???

cheers,



BlackXR5o, WAzz
 

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I have done something similiar

I did not mount a ct110 engine, but I have mounted an atc125m engine in a ct70 which is the same mounting as xr50. the 125 has the same mounting as the 110 so there are 3 mods you will have to do.



1. enlarge the front mounting hole. The hole on the ct110 is larger than that of the 50 so if you use a small botl it will wiggle



2. Grind the engine case because the engine mounting hole is wider.



3. fabricate 2 munting brackets so the back/bottom can hold.



Now, you will have to get a new front countershaft sprocket to fit since the chain is 428 and not 420.



Off to the races...
 

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YOu can't see it on my bike....

You cannot see where I ground because the the engine is mounted. On a ct70 frame it covers it up. For reference, measure the width of the xr50 mounts and then grind/cut the same amount off on both sides of the ct110 mounts. On the rear mount, I would do this:



take a 1/4" plate of steel about 1" wide x however long. Drill two holes in each one...one to mount to the frame and 1 to mount to the engine. Then, as before, measure the xr50 rear mount and grind/cut the ct110 mount to match minus 1/4" on each side. Then grind/cut those plates to fit and mount them up. If you use anything less than 1/4", I think it would be too weak and possibly break. Use washers for alignment.



Real simple to do and works like a charm. You will need a bandsaw to cut the plates and a drill press to cut the holes. Also, a die grinder with a cutoff wheel and grinder will be needed. Other than that, you are in.



As for wiring it, a ct110 is a cdi so you don't have to change anything...just run the correct wire to the harness and you are in.
 

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sprocket

Good to ask about the sprocket. No, it does not have the same sprocket. It also uses stock 428 chain. Instead, you need to go purchase a sprocket and sprocket holder from a ct70 and then you are in business. Dratv is your source for it.
 

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Discussion Starter · #13 ·
KCL said:
So, is the 70 motor and the 50 motor a direct replacement fit? They look almost identical is size to me.....Thanks.


model-------------------STOCK GEARING

CT70 69-71-----------------15-38

CT70 72-82----------------13-35

CT70H 70-72---------------13- 45

CT70 91-93 ----------------15-35



Does that help???
 

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And others as well...

You can put any ct70, xl70, sl70, cl70, s65, z50 engine in your fifty provided you correctly wire it. All these engines use points and condensor instead of cdi (except for the much later years). To make them run in your 50, all you have to do is run the wire from your coil to the black from the stator (most models) and it will run just fine.



I am just about finished building a monster sl70 engine with a 52mm bore and stroke, ported and polished race head, super cam and more. Haven't figured out the clutch yet, but still thinking about it. It could go in a 50, but I am putting it in a different frame for midsize racing.
 

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You all fail to mention points motors start harder, have a 6V electrical system instead of 12V and require more maintenance.



I build a good number of vintage minis, and will always put a 12V motor in the bikes. I hate 6V motors and points. Mine all run lights, and the 6V lighting stinks!
 

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That stuff is/is not true

Yes, the engines require maintenance, but I never thought that they were harder to start. My points engines are all 1 kickers and run like tops. CDI is certainly better but I really do enjoy the mechanical advancing mechanisms over the advancing CDI.



Lighting...yes, you have me there. The lighting on a 6v plain sucks even when you actually get it to work. But if you are running a 50 with no need for lighting, that really doesn't matter.



Problem is that performance parts are more designed for the new engines. But, here is what I do know...



I can get a complete bottom end from a 1971 sl70 on ebay for $75 shipped to my door. Take it down and completely rebuild it and add the following:



HD Clutch Springs - $10

52mm Stroker Crank - $130

52mm Piston, rings - $40

52mm Aluminum cylinder - $40

Gasket Set/Seal Set - $10

New Points/Condensor - $12

E22 head, with Cam ported and Polished - $65

HV oil Pump - $30

Grand Total - $337



And I have a 4-speed manual, 1-down 3-up manual clutch with a complete honda bottom end that will kill any 88cc kit on the market. I generally ride for pleasure, but I would put this engine up against any 88cc kit...
 

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Jared,



I'm with you on the cheap build costs. The only other problem I see with points motors is the points float you get when spinning them above 11K rpms.



But, there is more than one way to skin a cat, and as you are aware, there is no wrong way to build a good project.



Dan
 
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