I picked up an mr250 today :) It's in fairly good conditon. The only thing wrong with it is that its missing a throttle cable. I've been searching and cant find a replacement. If anyone knows where i could find one that would be great. Also any information about this bike would be great, I cant seem to find anything about it. thanks for any help
1976 Honda mr250
- Thread starter maschaff
- Start date
Not much here, except a lot of CR parts should work on that bike also. That was a detuned cr motor, in a trail frame with lights? Vintage Bob
2strokerfun
Member
- May 19, 2006
- 1,500
- 1
Honda will have a throttle cable that works. It's just a Keihin carb and standard throttle grip.
The MR is an enduro bike based on the '75 CR250r frame. They are great trail bikes. The differences between the 75-76 CR and the MR are basically: MR has a carbon steel frame with lugs for took kit, chain guard and engine case guard--CR has chromoly frame; MR has 3.2 gallon steel tank and longer seat--CR has 1.6 gallon aluminum tank and shorter seat; MR has points ignition ala 73-74 CR (different points, though)--most 75-76 CRs had CDI ignition; MR has same forks, but right casting has lug for speedo cable; MR has speedo, front and back light; rear shocks springs are different; MR has wide-ratio transmission--CR has close ratio; MR has exhaust port 1mm lower than CR; MR has 34mm Keihin carb with pilot, main and powerjet--CR has 34mm Keihin with different internals and only pilot and main (which still flows a bit more than the MR with three jets); MR has trail friendly huge flywheel and lugs like a four stroke down low--CR has quick revving very light flywheel; MR has four main head bolts and one small one--CR has four main and four small head bolts; MR footpegs are raised about 1/2 inch above those of CR (frame the same there, the pegs are different and I prefer MR pegs as you have more clearance to ground); MR frame is black and tank/side plates ruby red with white fenders--CR frame, tank and plastics are tahitian red; MR has steel shifter and rear brake pedal--CR has aluminum; Pipe and muffler look exactly the same (boat anchor mufflers on both) but there are slight differences you just cannot see.
What is the same is the piston, cases, lower end (except for gears); clutch and throttle cables; rear wheel; tires; plastics (except for color).
There are still a whole lot of MRs around and many people have CR'd them up a bit. I recommend a 13/48 gear set instead of the 14/48 factory setup. Also, a 36mm Mikuni carb jetted correctly helps. Remove the top of the airbox to open it up a bit BEFORE you jet it (after, and you just have to jet again). Also put on a copper CR head gasket to up the compression about a half a point. You can use a CR cylinder for a harder hit, too, but doesn't make that big of a difference. Take off the tool box, lights (35 watter doesn't do much anyway) and chain guard to lighten it up a bit.
Pistons still available from Wiseco or through dealer (make it easy and just ask for a 75-76 CR piston--they are the same and don't let anyone tell you a 73-74 CR piston will work as ring pins are in different places because of extra port on 75-76); bearings, seals, cables still available through dealer; sprockets through Sprocket Specialties (concave rear sprocket if you look); Plastics through aftermarket (choice of white or tahitian red). Lots of aftermarket stuff available including exhaust, if you want to plunk down $300.
Good luck !!
The MR is an enduro bike based on the '75 CR250r frame. They are great trail bikes. The differences between the 75-76 CR and the MR are basically: MR has a carbon steel frame with lugs for took kit, chain guard and engine case guard--CR has chromoly frame; MR has 3.2 gallon steel tank and longer seat--CR has 1.6 gallon aluminum tank and shorter seat; MR has points ignition ala 73-74 CR (different points, though)--most 75-76 CRs had CDI ignition; MR has same forks, but right casting has lug for speedo cable; MR has speedo, front and back light; rear shocks springs are different; MR has wide-ratio transmission--CR has close ratio; MR has exhaust port 1mm lower than CR; MR has 34mm Keihin carb with pilot, main and powerjet--CR has 34mm Keihin with different internals and only pilot and main (which still flows a bit more than the MR with three jets); MR has trail friendly huge flywheel and lugs like a four stroke down low--CR has quick revving very light flywheel; MR has four main head bolts and one small one--CR has four main and four small head bolts; MR footpegs are raised about 1/2 inch above those of CR (frame the same there, the pegs are different and I prefer MR pegs as you have more clearance to ground); MR frame is black and tank/side plates ruby red with white fenders--CR frame, tank and plastics are tahitian red; MR has steel shifter and rear brake pedal--CR has aluminum; Pipe and muffler look exactly the same (boat anchor mufflers on both) but there are slight differences you just cannot see.
What is the same is the piston, cases, lower end (except for gears); clutch and throttle cables; rear wheel; tires; plastics (except for color).
There are still a whole lot of MRs around and many people have CR'd them up a bit. I recommend a 13/48 gear set instead of the 14/48 factory setup. Also, a 36mm Mikuni carb jetted correctly helps. Remove the top of the airbox to open it up a bit BEFORE you jet it (after, and you just have to jet again). Also put on a copper CR head gasket to up the compression about a half a point. You can use a CR cylinder for a harder hit, too, but doesn't make that big of a difference. Take off the tool box, lights (35 watter doesn't do much anyway) and chain guard to lighten it up a bit.
Pistons still available from Wiseco or through dealer (make it easy and just ask for a 75-76 CR piston--they are the same and don't let anyone tell you a 73-74 CR piston will work as ring pins are in different places because of extra port on 75-76); bearings, seals, cables still available through dealer; sprockets through Sprocket Specialties (concave rear sprocket if you look); Plastics through aftermarket (choice of white or tahitian red). Lots of aftermarket stuff available including exhaust, if you want to plunk down $300.
Good luck !!
Huh, so every 100 miles it loses spark? One thing I always start with when doing renos, or repairs, is the ground. It is probably the most overlooked aspect of the electrical system. You must have a good ground for the system to work. Also checking for loose wires/connections/faulty kill switch.
MR250 No Spark
Thanks for your input. I have isolated each section of the wiring and checked for continuity. All was good. However, jumping the kill switch seems like a good idea, just to be sure. I may try new wire for the entire system (w/o kill switch). This has been so frustrating that I bought a 2012 XT250, just to have something to ride, as I figured this was not going to be solved overnight. The bike spent the entire winter at a Honda dealer, where an older gentleman, who was familiar w/ the older bikes, tried everything he knew, and still did not get spark. :yikes:
Thanks for your input. I have isolated each section of the wiring and checked for continuity. All was good. However, jumping the kill switch seems like a good idea, just to be sure. I may try new wire for the entire system (w/o kill switch). This has been so frustrating that I bought a 2012 XT250, just to have something to ride, as I figured this was not going to be solved overnight. The bike spent the entire winter at a Honda dealer, where an older gentleman, who was familiar w/ the older bikes, tried everything he knew, and still did not get spark. :yikes:
