The Mosquito! (KZ250)
- Thread starter scott s
- Start date
Re: The Mosquito!
And here's a sneak preview....
I ran out of daylight for better pics. It's about 98% done here. Still need to lube the chain, tune it just a tad, and I have some killer badges being made for the tank.
Oh, and I have a leaking petcock. I hate petcocks. I'm batting a thousand when it comes to petcock trouble. EVERY single bike I've ever built has had petcock issues.
And here's a sneak preview....
I ran out of daylight for better pics. It's about 98% done here. Still need to lube the chain, tune it just a tad, and I have some killer badges being made for the tank.
Oh, and I have a leaking petcock. I hate petcocks. I'm batting a thousand when it comes to petcock trouble. EVERY single bike I've ever built has had petcock issues.
Re: The Mosquito!
We did a little work on the rear brake. We were warned that the linkage we had fabbed up may be robbing us of some leverage. They were right...
We did two things:
1) Made a longer arm to be welded to the outside (with several holes for adjustment)
2) Drilled a lower hole on the inside arm of the pivot.
Doing these two things gave us back the leverage we needed. Excellent pedal feel and I can actually lock up the rear brake if I wanted to.
I may trim of the extra length on the outside arm, but leaving it there would provide adjustment for a future owner who may have shorter legs than me. There is also adjustment left in the rear set foot pegs, so the bike could be configured to fit a range of riders.
We did a little work on the rear brake. We were warned that the linkage we had fabbed up may be robbing us of some leverage. They were right...
We did two things:
1) Made a longer arm to be welded to the outside (with several holes for adjustment)
2) Drilled a lower hole on the inside arm of the pivot.
Doing these two things gave us back the leverage we needed. Excellent pedal feel and I can actually lock up the rear brake if I wanted to.
I may trim of the extra length on the outside arm, but leaving it there would provide adjustment for a future owner who may have shorter legs than me. There is also adjustment left in the rear set foot pegs, so the bike could be configured to fit a range of riders.
Re: The Mosquito!
Forgot to mention: I think we will adjust the brake and shift lever up just a tad. (Just the levers, not the pegs) I don't think I stand a chance of ever dragging either one, but if I leave my toes below the shift lever or have the rear brake on while making a RH turn, my feet/toes get a little close to the pavement.
Again, if I weren't so long legged and the bike wasn't so small, the pegs could be moved up. It is what is is, though and nothing but the tires have touched the pavement so far....knock on wood.
Forgot to mention: I think we will adjust the brake and shift lever up just a tad. (Just the levers, not the pegs) I don't think I stand a chance of ever dragging either one, but if I leave my toes below the shift lever or have the rear brake on while making a RH turn, my feet/toes get a little close to the pavement.
Again, if I weren't so long legged and the bike wasn't so small, the pegs could be moved up. It is what is is, though and nothing but the tires have touched the pavement so far....knock on wood.
Re: The Mosquito!
Took it out for a ~25 mile shake down run and discovered a few things....
A) It's LOUD! The home made baffle sounds mean and surprisingly deep for such a small bike, but I'm going to find the correct baffle for the stinger we used to make the mega-phone.
B) It vibrates like crazy. I need to replace a few lost nuts with nylon lock nuts and apply some blue lock-tite liberally to a few others.
C) It's very lean. Scarily lean. It never acted like it wanted to seize up, but my I.R. temp gun gave me readings of ~300 degrees on the cylinder when we got home and the spark plug is very white.
I did figure out that the carb is from an RD series Yamaha. I have a friend who is a 2-stroke guru and will ask his opinion on clip setting for the needle and maybe raid his parts bin for a larger main jet.
I got her up to 78 MPH and the tach showed a little over 7,000 rpm. Factory literature says max HP is at 9,000 rpm, so I either have an aftermarket tach that is reading off a little or she just plain ran out of gas.
I'll get some more fuel in the carb and try again, but I feel like it'll do 80+ eventually.
Oh, we also weighed it using the bathroom scale method and she's just over 250 lbs.
Some pics from the shake down run (I'm still waiting on my tank badges).
Took it out for a ~25 mile shake down run and discovered a few things....
A) It's LOUD! The home made baffle sounds mean and surprisingly deep for such a small bike, but I'm going to find the correct baffle for the stinger we used to make the mega-phone.
B) It vibrates like crazy. I need to replace a few lost nuts with nylon lock nuts and apply some blue lock-tite liberally to a few others.
C) It's very lean. Scarily lean. It never acted like it wanted to seize up, but my I.R. temp gun gave me readings of ~300 degrees on the cylinder when we got home and the spark plug is very white.
I did figure out that the carb is from an RD series Yamaha. I have a friend who is a 2-stroke guru and will ask his opinion on clip setting for the needle and maybe raid his parts bin for a larger main jet.
I got her up to 78 MPH and the tach showed a little over 7,000 rpm. Factory literature says max HP is at 9,000 rpm, so I either have an aftermarket tach that is reading off a little or she just plain ran out of gas.
I'll get some more fuel in the carb and try again, but I feel like it'll do 80+ eventually.
Oh, we also weighed it using the bathroom scale method and she's just over 250 lbs.
Some pics from the shake down run (I'm still waiting on my tank badges).
Re: The Mosquito!
In the above pics, you can see what I mean about the levers. I want to bring them both up to be a little more parallel to the ground and closer to the height of the pegs.
Here's the spark plug reading....YIKES! I guess we got lucky on this ride. We'll definitely do some adjustments before any further riding.
In the above pics, you can see what I mean about the levers. I want to bring them both up to be a little more parallel to the ground and closer to the height of the pegs.
Here's the spark plug reading....YIKES! I guess we got lucky on this ride. We'll definitely do some adjustments before any further riding.
Re: The Mosquito!
Luckily, I had purchased a muffler for this project a while back, before I changed directions and went with the stinger.
We simply cut the head pipe of, fabbed up a rubber mounted hanger and bolted it on.
Because of some carb tuning we're doing (and waiting on jets, needles, etc.), I haven't been able to hear it yet. I DO have a buddy that has a CB200 with a pair of these mufflers and it sounds pretty good....and MUCH more quiet than the KZ250 was!
Luckily, I had purchased a muffler for this project a while back, before I changed directions and went with the stinger.
We simply cut the head pipe of, fabbed up a rubber mounted hanger and bolted it on.
Because of some carb tuning we're doing (and waiting on jets, needles, etc.), I haven't been able to hear it yet. I DO have a buddy that has a CB200 with a pair of these mufflers and it sounds pretty good....and MUCH more quiet than the KZ250 was!
Re: The Mosquito!
Here's another look at the muffler. Also in this shot, notice that we adjusted the pedal position on the brake and shifter levers. I had a few people voice concern over them being too low, but this is a small bike and I'm a long legged guy.
I've been watched while riding it and I'm in no danger of dragging anything (if I'm leaning it that far over, it's too late anyway!), but my Dad did notice that the levers were the lowest point and may have put me in danger of catching my toes on something, especially when applying the rear brake. So, now they're a little more horizontal. And remember, these pegs are on the same plane as the stock pegs were.
Here's another look at the muffler. Also in this shot, notice that we adjusted the pedal position on the brake and shifter levers. I had a few people voice concern over them being too low, but this is a small bike and I'm a long legged guy.
I've been watched while riding it and I'm in no danger of dragging anything (if I'm leaning it that far over, it's too late anyway!), but my Dad did notice that the levers were the lowest point and may have put me in danger of catching my toes on something, especially when applying the rear brake. So, now they're a little more horizontal. And remember, these pegs are on the same plane as the stock pegs were.
Re: The Mosquito!
If the carb is from an RD350/400 it should have a 4 stroke type needle jet #175 series probably an )-8 which is a good place to start. Needle could be one of 4. Slow jet is probably #25 and that's easy to see if it's OK. See if it idles and responds to changes in the air screw. If teh air screw has to be almost all teh way in to get it to idle, go up to #27.5 or 30.
Main jet is probably 115 or 120 depending on what the carb came from. That may be too small for your motor.
Get the idle right first and then try a flat out run and do a plug chop and inspect the plug, go up a few plug sizes and repeat until you get it right and then go up one size. I'd guess you will end up closer to 130-140 but that's just a guess.
If the carb is from an RD350/400 it should have a 4 stroke type needle jet #175 series probably an )-8 which is a good place to start. Needle could be one of 4. Slow jet is probably #25 and that's easy to see if it's OK. See if it idles and responds to changes in the air screw. If teh air screw has to be almost all teh way in to get it to idle, go up to #27.5 or 30.
Main jet is probably 115 or 120 depending on what the carb came from. That may be too small for your motor.
Get the idle right first and then try a flat out run and do a plug chop and inspect the plug, go up a few plug sizes and repeat until you get it right and then go up one size. I'd guess you will end up closer to 130-140 but that's just a guess.
Re: The Mosquito!
The carb is from an R5. I've already gone up to a 130 main, 27.5 pilot, and dropped the needle clip to the lowest groove, which helped, but it's still on the edge. The jet needle os an O-0, which is the leanest they make for this carb.
Mercury Mike Morris at 650 Central just sent us a bag of jets, needles and mains. I've been out of town, but plan on starting carb tuning this week. He also suggested drilling out one of the air holes on the throat of the carb. He's been a huge help on this project (as well as with tuning the Mikunis on my Dad's XS650 bobber). Pay the money for his carb tech service......it's worth every penny. That guy REALLY knows his stuff.
The carb is from an R5. I've already gone up to a 130 main, 27.5 pilot, and dropped the needle clip to the lowest groove, which helped, but it's still on the edge. The jet needle os an O-0, which is the leanest they make for this carb.
Mercury Mike Morris at 650 Central just sent us a bag of jets, needles and mains. I've been out of town, but plan on starting carb tuning this week. He also suggested drilling out one of the air holes on the throat of the carb. He's been a huge help on this project (as well as with tuning the Mikunis on my Dad's XS650 bobber). Pay the money for his carb tech service......it's worth every penny. That guy REALLY knows his stuff.
sham
Been Around the Block
Re: The Mosquito!
Hey Scott,
I just came across this and its pretty cool what you've done with the bike. My z250 just got delivered today, so I'm hoping to start on it pretty soon - probably won't be able to do as much as you have as I don't really have access to welding or fabrication gear, but yours is definitely coming along nicely.
I'll be following this to get some ideas, and I'll probably bug you when I get stuck too!
Hey Scott,
I just came across this and its pretty cool what you've done with the bike. My z250 just got delivered today, so I'm hoping to start on it pretty soon - probably won't be able to do as much as you have as I don't really have access to welding or fabrication gear, but yours is definitely coming along nicely.
I'll be following this to get some ideas, and I'll probably bug you when I get stuck too!
Re: The Mosquito!
The Mosquito is doing OK. Sorry for the long pause between updates. It took me FOREVER to get the badges done. I actually had to retrieve them from one shop and found someone else to do them for me.
They're not quite as bold as I would have liked, but they turned out OK, don't ya think?
My only problem is that the silver prismatic background of the flags kind of clashed with the whit of the badges. They could both be white OR silver, but not mismatched, IMO. I'll probably look for some white/red flags for the side covers.
This pic are a little washed out from the sunlight, but...
The Mosquito is doing OK. Sorry for the long pause between updates. It took me FOREVER to get the badges done. I actually had to retrieve them from one shop and found someone else to do them for me.
They're not quite as bold as I would have liked, but they turned out OK, don't ya think?
My only problem is that the silver prismatic background of the flags kind of clashed with the whit of the badges. They could both be white OR silver, but not mismatched, IMO. I'll probably look for some white/red flags for the side covers.
This pic are a little washed out from the sunlight, but...
Re: The Mosquito!
The muffler is doing and sounding fine, except for a hanger bolt that vibrated loose on the last ride. I've already replaced it and used a self-locking washer, but the WORST part of that ride was the throttle cable breaking.
I THOUGHT I knew how to silver solder.....
Even a 250 lb. bike gets heavy when you have to push it half a mile to get off the main road and into a driveway so you can use the cell phone.
I was all set to try again using a solder pot when I found a throttle cable for a KZ200 that looks perfect and it was only $11.99 shipped. It's on the way and I'll let you know how that goes.
Until then, more gratuitous shots...
The muffler is doing and sounding fine, except for a hanger bolt that vibrated loose on the last ride. I've already replaced it and used a self-locking washer, but the WORST part of that ride was the throttle cable breaking.
I THOUGHT I knew how to silver solder.....
Even a 250 lb. bike gets heavy when you have to push it half a mile to get off the main road and into a driveway so you can use the cell phone.
I was all set to try again using a solder pot when I found a throttle cable for a KZ200 that looks perfect and it was only $11.99 shipped. It's on the way and I'll let you know how that goes.
Until then, more gratuitous shots...
