Front sprocket

[Alienation420]

Alright, my custom project is proving to be a bit more difficult than I anticipated!

My rear sprocket is from a lesser known brand, and I'm trying to find a matching sprocket. It is currently a 39t 428. I'm wondering if I can convert the drive sprocket on the motor to be a 428?

If not, I'll have to figure out how to change the rear to a 530!

 

[NewHavenMike]

Check out JT Sprockets.


http://www.jtsprockets.com/catalogue/model/2862/

Theres a tab lock washer on the front sprocket too that should be changed and also the nut has to be torqued.

 

[Alienation420]

Sounds good!

I haven't found anything when it comes to replacing the sprocket with a 428 though. I may have found a 530 rear sprocket that will work, but I'm going to wait until I have the actual motor to make the final decisions

 

[NewHavenMike]

Having a narrower chain for what? more tire clearance? Its recommended that you stick with a plain old roller chain.

 

[Alienation420]

The only reason being it seems to be easier to find a front 428 to match the 428 rear, rather than the other way around.

If you recommend sticking with the 530, then I could just get a blank 530 rear sprocket and have it custom milled to match my specs for the rear (center bore, bolt spacing)

 

[NewHavenMike]

Easiest would be to keep the stock setup. If all you have is the engine, the chain and sprocket should not even be a thought yet.. Theres an enduro/ dual purpose build on the XS400 homepage.

 

[Alienation420]

The build is going already, hence why I'm ironing out details. I know I'll have to modify the frame slightly for exhaust ports to clear.
I got my hands on a full running xs400 with no regi, so everything I don't need will be going up for sale!

 

[xschris]

I would stick to a 530 or 520 chain. 428 would be very weak for this motor. This motor should put out around 38-40 hp if it's running correctly. Make sure your setup cam handle that.

 

[Alienation420]

That's Xschris! I found a site that makes custom aluminum sprockets, so I can get one made in 530 for the rear.

 

[xschris]

Problem with those type is they will wear very fast. Often use for race bikes, as they are changed after each race.

 

[Alienation420]

So would you suggest a steel sprocket then? Aluminum wouldn't be good for long term? I'm building this bike for a 5000km trip this summer, so I need it to last.

The only steel blank sprocket I could find was a 38t. Would that work with the stock 16 front?

 

[xschris]

I run a 17 front and 37 rear with a 120/90-16 rear wheel/tire and a 16-37 with a 110/90-18 rear wheel. That is a good overall setup for town and highway use xs400. Bot setups run the motor at the same rpm's. Yes steel is going to out last any aluminum sprocket.

 

[Alienation420]

My rear tire is a 140/70-18. I'm sure the motor has a 16t front, but I can confirm that on Saturday. As for rear blanks, I can't find anything smaller than a 38t. My goal is to have a good all around bike, but this summer I'll be doing more highway than anything. (5000 km trip coming up). Should I drop down 1 tooth on the front? I'll type it into gearing commander and see, but I would prefer real world experience from people!