Motorbike forks for a minibike

[bighead]

nice welding friend. Is the jack shaft going on the plate or the bars behind the plate?

I recon that motor plate is never coming off. Solid weld down the whole plate. Good practice though right?

 

[landuse]

nice welding friend. Is the jack shaft going on the plate or the bars behind the plate?

I recon that motor plate is never coming off. Solid weld down the whole plate. Good practice though right?

Thanks Bighead. The jackshaft is going to go on the plate, not the bars. I have also welded the plate underneath, and want to put some more square tubing as bracing underneath as well. I don't think it will go anywhere either.

 

[landuse]

I got some more work done this weekend. On Friday I got all my sprockets back from the engineer. He had cut all the keyways into the sprockets and machined off the boss on my 48 tooth sprocket. He did a really good job. You can see everything together in the first 2 pics.

I then concentrated on the back brake. I have a mechanical caliper that came off a small Chinese quad, and I had to figure out how to mount it. I cut a piece of flatstock, using a wooden template that I had made, and then bolted the brake onto that. I then lined it up to spin freely on the brake disc. After welding it all on, I found that the warping of the metal had misaligned things a bit, so I will have to use a washer or two to line things up again.

I then got started on the jackshaft mount. I had to cut 2 lengths of square tubing and weld them together to form a base for the jackshaft to sit on. I then welded them to the motor mount. I then welded the two plates with the bolt holes onto it. You can see from the pic how it turned out. I put the engine in the frame to see what everything is going to look like.

I then had to get my clutch to fit on my engine properly. It would slide on and then get stuck halfway. I had to use a file and some sandpaper to get it fitting like a glove. Took me a while though.

I also spent some time on my front brake, trying to bleed it, but haven’t had any success yet. I will look at it again another time though.

 

[bighead]

Lookin great man. What color you going to paint it?

 

[landuse]

Lookin great man. What color you going to paint it?

I am not sure yet, I haven't really thought about it. I think I am just going to leave it to my daughter to decide.

I just hope I can get this thing going. The closer I get to the finish, the more doubts I get. It is the first time I have done anything mechanical, so I don't have a whole lot of confidence that I will get it working properly.

 

[j.concepcion54321]

hey, have you got any more work done on the bike? It was coming out sweet.

 

[landuse]

Thanks jconception. I have been away for the last 2 weekends, so I haven't had a chance to do anything more. Unfortunately I only have the weekends to do any work. At least I was at the beach!!

What I have done in the meantime though is bleed the front brakes. I just have to install them again. They are sitting on my workbench at the moment.

The second thing I did is take my engine to a small engine shop to have them sort out the engine idling and revving problem. I just could not sort it out myself. I should get it back before the weekend.

This weekend I will probably be bolting the engine down, installing the clutch, making sure the tyres hold air (haven't even checked that yet), amongst other things.

If I get far enough I might even be doing the throttle hookup.

Updates to come................

 

[landuse]

OK, so I didn't get much further with the bike this weekend. I did manage to get all the breaks sorted out. The front brakes I had to put on the left of the handlebars, cos the master cylinder I had was fitted for the left. They work really well now after I bled them.

The back breaks were also sorted out. The plate that the mechanical caliper is bolted to has warped a bit when I welded it on, so I had to use a couple of washers as spacers to get the caliper lined up nicely with the brake disc again.

I also checked to see if the tyres hold air, and it seems like the back wheel will need a new tube.

Unfortunately I didn't get the engine back from the shop, so I couldn't start drilling the engine mount holes. I also have to buy some more chain, cos I don't have enough for everything.

So what I still gotta do is

• Connect the back brake to the handlebar lever
• Mount the engine
• Bolt my jackshaft to its mount
• Get tube for back tyre
• Mount clutch and make sure it works properly
• Fasten seat to the frame (easy)
• Strip all paint off for painting (a pain cos I think its powdercoated)
• Hook the throttle up to the engine

Thats pretty much what I can think of at the moment, but I'm sure there is going to be loads more to be done before I am finished. I am at that stage where all the fine detail take time and you don't seem to make any progress.

 

[landuse]

Right….So I managed to get quite far with my bike this weekend. The checklist that I posted above is pretty much done. I got my engine back from the shop on Friday, so I was all ready for the weekend.

I first mounted my clutch to check if it works OK reversed, and it worked brilliantly. Anderkart…you were right that I didn’t need to drill any hole in the clutch drum; I just turned the insides of the clutch around as well so that the grub screws faced outwards.

I then started on getting the jackshaft bolted down and the chain on, when I realised that the chain was going to hit the frame, so I had to grind away one of my supports, and cut away some of my sheet metal floor to accommodate the chain. I then welded another support on the bottom to replace the one I had taken out. You can see in the pics what I did to sort it out.

I then bolted the engine down to the mounting plate and started sorting out the chain. The chain from jackshaft to the back wheel is nice and tight, but the one from the clutch to the jackshaft is very loose. I am going to have to get a half link or something, because it is not slack enough to take another link out. It is funny how much of a difference one link could make.
I then started with attaching the back brake to the handle lever. I got it all sorted out, but now the brake is giving me problems. I am going to have to adjust it again.

Yesterday I did the throttle connection. I got a couple of pics of this site to give me some idea on how to go about it. I had to connect two pieces of wire, so I just used someone here’s idea (can’t remember who) of taking a metal tube, putting the cable in and smacking it flat. I connected everything like it should be.

I have a problem now though. My engine for some reason just doesn’t want to rev high. I will make another post though to discuss that with pics.

 

[landuse]

I have a problem now though. My engine for some reason just doesn’t want to rev high. I will make another post though to discuss that with pics.

Like I said above, I pretty much have my throttle linkage sorted out. The only problem I have now is that the engine doesn’t seem to rev even close to the 3600rpm that it should. Because of this, the clutch is slipping big time. Even when the throttle gets pulled from the one stop to the other, it still doesn't rev high. When I say 'stop' I mean from a total idle to where the butterly linkage can't go any further.

If you guys could have a look at the pics of my throttle and carb connections and tell me if I am doing something wrong, I would appreciate it. Maybe I should change something. I took the shroud off the front of the engine so that you could see the governor linkages as well.

My daughter is getting on my back to get this thing done, and I don’t want some possible stupid thing holding me back. You guys are the experts , so I thought I would ask you first.

 

[landuse]

Any ideas on the engine??

 

[Leftythenub]

The gearing looks like it about a 1 to 1 ratio. Flip the jackshaft sprockets around. Engine should be small on clutch to larger on jackshaft. small on sackshaft to larger on wheel. It looks like you have small to small and large to large. Your clutch will never lock up with that gearing.

 

[landuse]

I have a 16 tooth clutch going to a 14 tooth sprocket on the jackshaft. From the jackshaft to the wheel I have a 38 tooth to a 48 tooth on the wheel.

Edit: I have just looked at my jackshaft calculations (that were provided to me by people on this forum long ago), and I have just figured out that I made a huge mistake putting the 14th sprocket on the jackshaft 'in' and the 38 on the 'out'. It should have been the other way around.

I will sort that out and let you guys know what happens. Its a good thing I didn't weld them on like I was going to do originally.

 

[landuse]

OK...so yesterday I bought a couple of return springs for my throttle, so I will see if I can get that sorted out soon. I also stopped off at the place that serviced my engine and asked them about the low revving. They said I must first try regearing, and if it is still a problem, they will come out to my house and check it out for me. (I think they just want to check the funny contraption out that I am making).

I cant wait to ride this thing......I am so close I can taste it

 

[brandongeiger2]

Well those are conventional style forks found normally on enduro dirt bikes, sport bikes, pit bikes, etc there very easy to work on

First of all your gonna want to take the forks out of the triple clamps

Next your gonna need to take a wrench or socket and unscrew the caps(be careful the cap is pressurized by the spring inside)

Once that's done pour all the oil out of them by tipping them over into a bucket or something.

Next you need to simply pull out the spring check if its seized up on anything...it probably is if its not compressing so you might also be able to just tap the top tube of the fork and itll loosen up.

After all that you need to disassemble the fork tubes and seals )located under the rubber boot and clean than reassemble you could re use the oil but i really wouldn't advise i would use maxima 10 weight motorcycle fork oil since its a light bike.

sorry bout the length of this post i got a little carried away
brandon

 

[Bluethunder3320]

with the air vane governor.. id just remove it. so easy to.

 

[landuse]

with the air vane governor.. id just remove it. so easy to.

Thanks. How would I remove the governor, and then what would I connect the throttle to? Could you maybe show me using my pics I posted above?

 

[landuse]

Well I finally got the bike finished and took it for a spin. The torque is pretty low, but it moves me OK. Here is the vid of my running minibike. No build is complete without a vid.

http://www.youtube.com/watch?v=GhxsNNXaqXo

The engine is still giving me some problems, but I should sort that out soon though. As I give full throttle, the engine seems to want to die. If I let off the throttle it starts running again.

Tell me what you think.

I CANT BELIEVE THAT i MADE SOMETHING THAT ACTUALLY RUNS!!!

 

[r97]

if i had to guess i would say your having a problem with it being lean, check for air leeks, clogged carb, or maybe replace the diaphragm.

aside from that it looks great!

 

[j.concepcion54321]

hey, great job on the bike landuse!! From the start i knew that 3hp would be a little low but i didnt say anything. I think that you should invest in a new engine. Something over 5hp. And then remove the governor and you should be happy. That bike looks really cool and IMO the speed is dissapointing. Congrats on the build though!!!