Final questions on MBX10 engine upfit
I really like my motovox. I put started out just drilling the engine bolt pattern in the engine plate(no adaptor plate) for a predator and with a shotgun header and open air filter and 12/75 gearing it would do 38 mph with lots of torque. I then added the mbx 11 forks which really helped the handling in the rough off road terrian. I bought a refurbished rolling chassis for $150, predator $100, header and air filter $80 and tires $50. For less than $400 I have a real decent minibike.....
But then I built an 8000rpm 208cc predator and turned it into a real quick minibike. I have it geared with a high ratio 11/75 and it will still hit 50mph and will break the rear tire loose and wheelie pretty much anytime you want. Super fun! And so far unbeatable around my yard race track.haha
Here is a picture of my vox.
But then I built an 8000rpm 208cc predator and turned it into a real quick minibike. I have it geared with a high ratio 11/75 and it will still hit 50mph and will break the rear tire loose and wheelie pretty much anytime you want. Super fun! And so far unbeatable around my yard race track.haha
Here is a picture of my vox.
Alright everyone, thanks for all the input!
Today when my fiancee was at work, I did most of the job myself. I am a very concrete, black-and-white person, whereas she is abstract and artistic, so it took her help to smooth out some of the bumps in the road that I encountered. For instance, she figured out how to remove the rear chain guard retainer without just cutting it all up (as I wanted to do), and she removed the muffler when I was content to keep bashing it with a sledgehammer.
Day 1 of the project is over. Should finish it up tomorrow. I need to re-run the chain, check the tension, tighten all the engine mount bolts, run the throttle cable, wire the kill switch, then we are ready for a test drive!
Progress photos...
Trip to the local hardware store for two 3/4" ID washers, plus Lowe's-sourced clutch bolt and washer, equals success:
Tight fit between the engine cowling and footpeg...have to see how comfortable this is when riding. Messy background is due to wheeling the bike into the garage and then deciding to do photos as an afterthought.
Exhaust was originally bashed with a sledgehammer, then removed to fit in the frame. It was reattached after the engine was mounted, with room to spare. Yes, this will be replaced with a real pipe sometime before next spring.
Clean rear end with no plastics for the moment. I know I routed the chain wrong and under the tensioner, have to redo that tomorrow. Anyone want a nice, near-new stock engine for free? It's luring in the background here.
Overall a nice fit, I am pleased. Thanks to all of you!!!
Today when my fiancee was at work, I did most of the job myself. I am a very concrete, black-and-white person, whereas she is abstract and artistic, so it took her help to smooth out some of the bumps in the road that I encountered. For instance, she figured out how to remove the rear chain guard retainer without just cutting it all up (as I wanted to do), and she removed the muffler when I was content to keep bashing it with a sledgehammer.
Day 1 of the project is over. Should finish it up tomorrow. I need to re-run the chain, check the tension, tighten all the engine mount bolts, run the throttle cable, wire the kill switch, then we are ready for a test drive!
Progress photos...
Trip to the local hardware store for two 3/4" ID washers, plus Lowe's-sourced clutch bolt and washer, equals success:
Tight fit between the engine cowling and footpeg...have to see how comfortable this is when riding. Messy background is due to wheeling the bike into the garage and then deciding to do photos as an afterthought.
Exhaust was originally bashed with a sledgehammer, then removed to fit in the frame. It was reattached after the engine was mounted, with room to spare. Yes, this will be replaced with a real pipe sometime before next spring.
Clean rear end with no plastics for the moment. I know I routed the chain wrong and under the tensioner, have to redo that tomorrow. Anyone want a nice, near-new stock engine for free? It's luring in the background here.
Overall a nice fit, I am pleased. Thanks to all of you!!!
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Yeah, exhaust is definitely next on my list!
Thanks to all who have chimed in on my thread. I am not the most skilled person at hands-on projects as my dad usually helped me with my minibike and go-cart when I was a kid, but I am learning and trying! Some of you are clearly gifted in all of these things, and I admire that.
I have encountered a couple problems at the last minute that prevent my from making progress. Looking for some insight.
1) Am I supposed to use the stock chain, or a stock length chain? Right now my second stock chain is still in the mail and I am working with the original. The only way I can get it to fit (it seems too short) is to invert the clutch (thanks to the idea above!) and then bypass the tensioner (as shown in photos last night). Yes it fits, but doesn't seem right.
2) The throttle cable-- arrgh! Biggest headache today! First of all I have not decided how to route it and have yet to get any good solid ideas on that. I have been looking at photos here on the forum but just can't make it out. But that's the least of my problems. I will try to explain this in words and photos the best that I can. I am an older person and not good enough with computers to know how to do things like draw little arrows on the photos to explain what I mean. Anyhow, I could not fit the cable through what I would call the primary approach for it that I would prefer (cable entering the engine throttle assembly perpendicular to the right side of the bike). Even with help from my fiancee, I could not get the throttle cable retaining screw to loosen within the nut. So I have routed it through the rear of the engine throttle assembly. However I am not sure if it is the engine, or these engines in general, but the throttle return spring seems worthless. I can hook up the throttle cable properly, but then it binds when it goes wide open, and does not return to what would be a lower RPM setting. It requires some hand strength to move, as if the throttle "lever" that came on the engine is meant to be manually adjusted. I hope that makes sense. In other words, I would probably ride the bike, but once I twisted the throttle open, it won't back off and return to a lower RPM because the throttle on the engine sticks.
Also there does not seem to be much travel range in the throttle cable, so to speak, it seems to move maybe an inch and not over the whole range of the engine's throttle movement.
Unfortunately for some reason I can't load the photos of how I have it now....will keep trying later.
Thanks to all who have chimed in on my thread. I am not the most skilled person at hands-on projects as my dad usually helped me with my minibike and go-cart when I was a kid, but I am learning and trying! Some of you are clearly gifted in all of these things, and I admire that.
I have encountered a couple problems at the last minute that prevent my from making progress. Looking for some insight.
1) Am I supposed to use the stock chain, or a stock length chain? Right now my second stock chain is still in the mail and I am working with the original. The only way I can get it to fit (it seems too short) is to invert the clutch (thanks to the idea above!) and then bypass the tensioner (as shown in photos last night). Yes it fits, but doesn't seem right.
2) The throttle cable-- arrgh! Biggest headache today! First of all I have not decided how to route it and have yet to get any good solid ideas on that. I have been looking at photos here on the forum but just can't make it out. But that's the least of my problems. I will try to explain this in words and photos the best that I can. I am an older person and not good enough with computers to know how to do things like draw little arrows on the photos to explain what I mean. Anyhow, I could not fit the cable through what I would call the primary approach for it that I would prefer (cable entering the engine throttle assembly perpendicular to the right side of the bike). Even with help from my fiancee, I could not get the throttle cable retaining screw to loosen within the nut. So I have routed it through the rear of the engine throttle assembly. However I am not sure if it is the engine, or these engines in general, but the throttle return spring seems worthless. I can hook up the throttle cable properly, but then it binds when it goes wide open, and does not return to what would be a lower RPM setting. It requires some hand strength to move, as if the throttle "lever" that came on the engine is meant to be manually adjusted. I hope that makes sense. In other words, I would probably ride the bike, but once I twisted the throttle open, it won't back off and return to a lower RPM because the throttle on the engine sticks.
Also there does not seem to be much travel range in the throttle cable, so to speak, it seems to move maybe an inch and not over the whole range of the engine's throttle movement.
Unfortunately for some reason I can't load the photos of how I have it now....will keep trying later.
If the chain isn't too sloppy(or even if its kinda tight) without the tensioner wheel go ahead and run it without. Then as you put some time on your bike, the chain will stretch and you might be able to put the tensioner back on(I have done this on db30s, might not work on the motovox). Or you could cut your new chain a couple links longer and use the tensioner right away.
As far as the throttle lever, you need to loosen the nut on the pivot stud so the lever can move freely and return to slow idle with a light return spring.
Here's a picture of how I setup my throttle using the original motovox twist throttle and cable.
I have a pencil pointing at the nut you have to loosen up so your throttle works freely.
Hope I could help.
As far as the throttle lever, you need to loosen the nut on the pivot stud so the lever can move freely and return to slow idle with a light return spring.
Here's a picture of how I setup my throttle using the original motovox twist throttle and cable.
I have a pencil pointing at the nut you have to loosen up so your throttle works freely.
Hope I could help.
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Thank you! I now have the throttle return spring behaving well.
Oiled 'er up, gassed 'er up, and...nothing! I pulled and pulled and she won't start. Tried moving the throttle to about 1/3 as the manual says, but no luck. It backfired twice but won't start. Been pulling for about 15 minutes now. Any ideas?
ETA: For what it's worth, I have not changed the kill switch wiring yet. Still the Predator factory kill switch.
Oiled 'er up, gassed 'er up, and...nothing! I pulled and pulled and she won't start. Tried moving the throttle to about 1/3 as the manual says, but no luck. It backfired twice but won't start. Been pulling for about 15 minutes now. Any ideas?
ETA: For what it's worth, I have not changed the kill switch wiring yet. Still the Predator factory kill switch.
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Must be some kind of problem. So your plug doesn't sound like its fouled..can you tell if there is fuel in the carb? Them predator engines usually start very easy. Make sure your plug is dry to start out and try to figure if you have gas in the carb and them see if its getting to the combustion chamber.
Do you still have the low oil sensor in the engine? If the engine is tilted enough it will prevent the motor from starting. I alway disconnect mine as soon as I take them out of the box. You don't really need to remove it from inside the motor, but it never hurts to take it out when you've got the motor opened up.
A new spark plug may help. The clone on my kart was giving me fits the other day, and as soon as I threw the new spark plug in...BOOM! It fired right up. I think I stuck an NGK in there this time. It may help, although it sounded like you may have had spark on the old one if it was backfiring.
A new spark plug may help. The clone on my kart was giving me fits the other day, and as soon as I threw the new spark plug in...BOOM! It fired right up. I think I stuck an NGK in there this time. It may help, although it sounded like you may have had spark on the old one if it was backfiring.
Aaaaand...SHE LIVES!!!
Thanks to davidlamb78 for the low oil sensor suggestion...that was the problem! Disconnected it and she fired right up and purrs like a kitten!
I rode around my yard, which is pretty flat, for five minutes or so to familiarize myself. The throttle response is weird and will take some getting used to.
Went out in the woods (no trails), threw the chain in about two minutes, then broke the chain a couple minutes later. I am guessing it's not a good idea to keep on the throttle when the bike gets stuck? I don't remember ever breaking a chain on a minibike when I was a kid, but I remember it constantly on an EZ Rider go-cart that I had.
Thanks to davidlamb78 for the low oil sensor suggestion...that was the problem! Disconnected it and she fired right up and purrs like a kitten!
I rode around my yard, which is pretty flat, for five minutes or so to familiarize myself. The throttle response is weird and will take some getting used to.
Went out in the woods (no trails), threw the chain in about two minutes, then broke the chain a couple minutes later. I am guessing it's not a good idea to keep on the throttle when the bike gets stuck? I don't remember ever breaking a chain on a minibike when I was a kid, but I remember it constantly on an EZ Rider go-cart that I had.
Thanks chipper...I ordered one of those chains!
I am guessing that the chain really stretched during that first ride, as I had almost zero time on the chain with the OEM engine. I put a master link in, still found that the chain fit sloppy, then lo and behold it was finally slack enough to properly route around the tensioner. Now she drives beautifully and the chain is great!
Chain's path appears to be nearly perfectly-straight to the naked eye.
Near future plans: proper chain guard, redo rear plastics, proper or new air box, better exhaust.
Here are some photos from today:
I am guessing that the chain really stretched during that first ride, as I had almost zero time on the chain with the OEM engine. I put a master link in, still found that the chain fit sloppy, then lo and behold it was finally slack enough to properly route around the tensioner. Now she drives beautifully and the chain is great!
Chain's path appears to be nearly perfectly-straight to the naked eye.
Near future plans: proper chain guard, redo rear plastics, proper or new air box, better exhaust.
Here are some photos from today:
