It Runs!! (Wombat)
Posted: Tue Aug 20, 2013 3:37 am
Puffie40 - 09/02/11 at 2:42pm
Holy Cripe, That felt like it took forever!
One parts bike, Hours of tinkering and a bunch of parts orders later, I got the little guy running!
Before:
After:
-almost all the rubber parts replaced
-Engine bored .02 oversize, modded for a reed valve and ported for trail riding (Thank you very much Rich!)
-MZ-B ignition
Unfortunately, it is just in time for me to park it to go back to school, so I don't have any more time to work out any of the bugs (It's running lean enough that I need the choke on all the time, I want to rework the air intake a little and there is still some bugs with the electrical system)
Oh well, one thing at a time!
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Bullfrog - 09/02/11 at 7:44pm
Um, don't mess around with the bike before adjusting the jetting. If you have the stock carb - simply making the reed valve changes will require a richer pilot jet, slide, needle position and perhaps 4 sizes richer on main jet. Operating the engine with lean jetting is asking for trouble.
Nice job! You are going to have some big time fun.
Ed
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Puffie40 - 09/03/11 at 8:27pm
The short time I rode it (I only took a couple of 3-5min spins with it to see what it was like) I think it has the same power as the old '84 XR200 I normally ride.
I took the carb (28mm from SH) off while putting it in storage, dug up the jets dad had in his toolbox (In a ace100 toolbag!) and tinkered with it a little. It had a 190 Main and a 25 pilot, so I put in a 230 Main, 30 Pilot and raised the needle a notch. I'll have to see what it does (Hopefully around thanksgiving)
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Puffie40 - 06/19/12 at 11:29am
So I dusted off the Wombat yesterday and got some tuning done. I had to lean it out quite a bit- down to a 160 MJ and I might try a 150 as I think the top end is still a little on the rich side.
There seems to be, as dad calls it, a "flat spot" just above idle, where the motor seems to have no power (it is really apparent when you are starting out). I put in the richest pilot jet I have - 45- but the air screw still needs to be almost closed to get any kind of decent throttle response. I'm at a loss at what I should do. any ideas?
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Bullfrog - 06/19/12 at 12:35pm
Puffie:
I am in the throes of panic getting ready for Hodaka Days, so I can't spend much time typing but . . .
1. Is this a stock piston-port engine? Or has it had a reed valve installed? If stock piston port, 25 pilot jet is "stock" - a 45 should be so rich that it wouldn't run well at all down at 0 to 1/8th throttle. However, if a reed valve has been installed, 40ish should be about right.
2. Sounds like the slide cut-away could be lean . . . which might match up well with adding a reed valve but not changing the slide. Std slide is 2.5 . . . but a 2.0 or 1.5 would likely be needed if reed has been installed.
OK. Bye for now . . . I have Hodaka Days stuff to tend to.
Ed
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Puffie40 - 06/19/12 at 9:19pm
Yeah, this Hodie has a reed valve in it.
Thanks for the advice. I didn't think about changing out the slide, so I got a 2.0 on order, along with a few more pilot and main jets.
Hope you have fun at Hodaka Days. I wanted to go but work is getting in the way.
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Bullfrog - 06/20/12 at 1:08am
There is high potential for "ouch" till you get the jetting worked out. Since air travels through the carb in only one direction with the reed valve, jetting has to be "richer" in order to deliver enough fuel in "one go".
Piston port jetting (for the same engine but without reeds) is commonly "leaner" because the air picks up some fuel going through the carb the 1st time . . . then a small portion of that fuel/air mix moves backwards through the carb and picks up a bit more fuel . . . then flow reverses again and that small "double fuel load" portion gets to pick up even a bit more fuel. So the smaller jets get 3 tries to deliver the proper amount of fuel.
Since the reeds eliminate that backward flow and the "repeat" flow, richer jets are required. On a Hodie, it is common to run about 4 sizes richer than stock on the main jet when reeds are installed.
Ed
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joebat - 06/23/12 at 10:06am
Puffie,
Bike looks great! I also have a Wombat reed valved and a 28 mm carb from a Super Rat on it. This carb is different than a Combat carb so I don't know which one you have. Mine is spigot mount. Anyway, I did get mine tuned well with a #30 pilot jet, 5F3 needle set at middle position (main nozzle needle jet is stock for this carb at N-8), and a 220 main. The Throttle Valve is also stock for this carb at 2.5. While tuning I did at one time have that 'dead' spot just about at 1/4 throttle and I know I am set richer now so, be careful! A 150 main sound very lean! Shocked
PS: Also an IMPORTANT note. I had to open up the air cleaner also, even when I still had a 24mm carb on it. Take the cover off of the cleaner and see what happens but get it RICH first!
And have FUN!
Joe
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Puffie40 - 06/25/12 at 3:14am
My eyebrows are a little raised at how lean the main jet wound up being, but it "four-strokes" pretty good if it is any richer, and the motor is okay for heat after a five minute test run of full-throttle running. The abnormally lean jetting may be because I am still using the stock, unaltered air cleaner (haven't gotten around to modding it yet.)
I'm using a 28mm spigot carb that is brand new from SH. The first bike did not have a carb on it, so I thought I would 'rod it out a little.
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joebat - 06/25/12 at 8:53pm
If you truly are running rich with a 150 main then something might not be right. Yes, your air cleaner may be starving the bike of air. Open it up when you can and get the power it is capable of!
Joe
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END OF THREAD
Holy Cripe, That felt like it took forever!
One parts bike, Hours of tinkering and a bunch of parts orders later, I got the little guy running!
Before:
After:
-almost all the rubber parts replaced
-Engine bored .02 oversize, modded for a reed valve and ported for trail riding (Thank you very much Rich!)
-MZ-B ignition
Unfortunately, it is just in time for me to park it to go back to school, so I don't have any more time to work out any of the bugs (It's running lean enough that I need the choke on all the time, I want to rework the air intake a little and there is still some bugs with the electrical system)
Oh well, one thing at a time!
___________________________________________________________________________________________
Bullfrog - 09/02/11 at 7:44pm
Um, don't mess around with the bike before adjusting the jetting. If you have the stock carb - simply making the reed valve changes will require a richer pilot jet, slide, needle position and perhaps 4 sizes richer on main jet. Operating the engine with lean jetting is asking for trouble.
Nice job! You are going to have some big time fun.
Ed
___________________________________________________________________________________________
Puffie40 - 09/03/11 at 8:27pm
The short time I rode it (I only took a couple of 3-5min spins with it to see what it was like) I think it has the same power as the old '84 XR200 I normally ride.
I took the carb (28mm from SH) off while putting it in storage, dug up the jets dad had in his toolbox (In a ace100 toolbag!) and tinkered with it a little. It had a 190 Main and a 25 pilot, so I put in a 230 Main, 30 Pilot and raised the needle a notch. I'll have to see what it does (Hopefully around thanksgiving)
___________________________________________________________________________________________
Puffie40 - 06/19/12 at 11:29am
So I dusted off the Wombat yesterday and got some tuning done. I had to lean it out quite a bit- down to a 160 MJ and I might try a 150 as I think the top end is still a little on the rich side.
There seems to be, as dad calls it, a "flat spot" just above idle, where the motor seems to have no power (it is really apparent when you are starting out). I put in the richest pilot jet I have - 45- but the air screw still needs to be almost closed to get any kind of decent throttle response. I'm at a loss at what I should do. any ideas?
___________________________________________________________________________________________
Bullfrog - 06/19/12 at 12:35pm
Puffie:
I am in the throes of panic getting ready for Hodaka Days, so I can't spend much time typing but . . .
1. Is this a stock piston-port engine? Or has it had a reed valve installed? If stock piston port, 25 pilot jet is "stock" - a 45 should be so rich that it wouldn't run well at all down at 0 to 1/8th throttle. However, if a reed valve has been installed, 40ish should be about right.
2. Sounds like the slide cut-away could be lean . . . which might match up well with adding a reed valve but not changing the slide. Std slide is 2.5 . . . but a 2.0 or 1.5 would likely be needed if reed has been installed.
OK. Bye for now . . . I have Hodaka Days stuff to tend to.
Ed
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Puffie40 - 06/19/12 at 9:19pm
Yeah, this Hodie has a reed valve in it.
Thanks for the advice. I didn't think about changing out the slide, so I got a 2.0 on order, along with a few more pilot and main jets.
Hope you have fun at Hodaka Days. I wanted to go but work is getting in the way.
___________________________________________________________________________________________
Bullfrog - 06/20/12 at 1:08am
There is high potential for "ouch" till you get the jetting worked out. Since air travels through the carb in only one direction with the reed valve, jetting has to be "richer" in order to deliver enough fuel in "one go".
Piston port jetting (for the same engine but without reeds) is commonly "leaner" because the air picks up some fuel going through the carb the 1st time . . . then a small portion of that fuel/air mix moves backwards through the carb and picks up a bit more fuel . . . then flow reverses again and that small "double fuel load" portion gets to pick up even a bit more fuel. So the smaller jets get 3 tries to deliver the proper amount of fuel.
Since the reeds eliminate that backward flow and the "repeat" flow, richer jets are required. On a Hodie, it is common to run about 4 sizes richer than stock on the main jet when reeds are installed.
Ed
___________________________________________________________________________________________
joebat - 06/23/12 at 10:06am
Puffie,
Bike looks great! I also have a Wombat reed valved and a 28 mm carb from a Super Rat on it. This carb is different than a Combat carb so I don't know which one you have. Mine is spigot mount. Anyway, I did get mine tuned well with a #30 pilot jet, 5F3 needle set at middle position (main nozzle needle jet is stock for this carb at N-8), and a 220 main. The Throttle Valve is also stock for this carb at 2.5. While tuning I did at one time have that 'dead' spot just about at 1/4 throttle and I know I am set richer now so, be careful! A 150 main sound very lean! Shocked
PS: Also an IMPORTANT note. I had to open up the air cleaner also, even when I still had a 24mm carb on it. Take the cover off of the cleaner and see what happens but get it RICH first!
And have FUN!
Joe
___________________________________________________________________________________________
Puffie40 - 06/25/12 at 3:14am
My eyebrows are a little raised at how lean the main jet wound up being, but it "four-strokes" pretty good if it is any richer, and the motor is okay for heat after a five minute test run of full-throttle running. The abnormally lean jetting may be because I am still using the stock, unaltered air cleaner (haven't gotten around to modding it yet.)
I'm using a 28mm spigot carb that is brand new from SH. The first bike did not have a carb on it, so I thought I would 'rod it out a little.
___________________________________________________________________________________________
joebat - 06/25/12 at 8:53pm
If you truly are running rich with a 150 main then something might not be right. Yes, your air cleaner may be starving the bike of air. Open it up when you can and get the power it is capable of!
Joe
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END OF THREAD