Moriwaki hose routing question

I have a stock 2008 MD250H. At some point someone decided to re-route all the vent hoses on the bike into one bottle (the radiator overflow); I know that is not correct and I'd like to put it back the way it is SUPPOSED to be, but I don't know where they are supposed to go. The service manual does not show them, I'm hoping someone here can help.

Here are my questions:
1) There is a connection on the frame rail that I know is designed to catch oil, what is supposed to be connected to that?
2) Where is the crankcase breather tube supposed to go? Does the open end just sit in the airbox?
3) There is a vent hose from the valve cover - where is that supposed to go?
4) There is a one-way valve on the gas tank vent tube (allows air to come in but no liquid to come out), but after the valve it also routes to a catch bottle, which doesn't make sense to me - can I eliminate the catch bottle, or should that valve not be there?

I have the radiator overflow hose going to a catch bottle strapped to the frame of the bike, I think at least THAT one is where it belongs.

Thanks in advance!

 

We haven't had Tyler's for a few years. so I'm going off an old guy's memory.

1. There was a greenish, braided long hose, that went from the left frame rail through/accross the top of the airbox, ran along the right side of the airbox, curved over and terminated by the mouth of the carb.
2. Yes it comes straight up into the air box.
3. That runs over to the left frame rail. This allows the frame to catch the extra oil. There is a drain bolt on the left frame rail, towards the swing arm pivot. If you run the engine full, it will continually spit oil in there. We seemed to have best results running it at the bottom level on the dip stick.
4. That is how ours was too, with the valve.

FYI, we quit running the airbox. Supposedly adds a fraction of power, but we did it to more easily reach the choke.

 

Rob! You are the best, thanks so much for this information, this is really, really helpful. The oil-spitting has been an intermittent issue - my current mechanic worries about how little oil this thing holds and maybe overfilling it because of that.

It has a CHOKE? I didn't even know that - prior owner just told me to partially cover the air intake during starting if I needed choke, and that does work. Good idea on removing the airbox, and I'll look for the choke.

So, let me see if I am understanding this right - the hose from the valve cover goes into a connection low on the left frame rail, where presumably any oil will catch in the frame rail, and the hose at the top is a the air breather/pressure relief for that? So effectively the frame rail works like a catch bottle with a vent hose at the top?

Everything you said aligns well with what I remember about the routing from before a mechanic re-arranged everything.

This really is a big help, thanks for taking the time to answer. (BTW, I taked to you a while ago about how the bike would stall for no apparent reason - we finally just replaced the entire wire harness and that solved it, it's running great now.)

 

Yea, they don't hold much oil. I checked ours every day and sometimes during the day. Occasionally I had to add a bit.

Choke is on the left side and pulls out. I think it is a red knob, but don't remember.

Yes on the hose connections and frame acting as catch bottle. We bought ours used too, no manual, and I never noticed the drain. Another racer dad pointed it out for me.

Is this Laura from S. Cal? If not, she had an intermittent stalling problem too, so I will let her know about your fix.

Glad I could help. They are great bikes.

 

Yes, that is me. I never did find the actual problem but the new harness seems to have fixed it.

Between the Moriwaki and the SuperSingle I am learning more about tuning and working on the bikes myself than I ever wanted to know - not too many people have experience with either of these types of bikes, I sure am glad there are people like you willing to share their knowledge!

 

Pretty good memory old man! Haha

 

The later model airboxes were much improved. The earlier airbox back wall was so close to the velocity stack that it impaired airflow. The later boxes had a step in the back to allow more distance between the stack and wall of the airbox. Using the term "airbox" is a bit of a misnomer....it is actually nothing more than a heat shield. Remove the airbox and flip the intake manifold 180 degrees and you will gain some HP.
BTW it does not have a "choke"...it is an enrichener. It is also a plus to add an extended A/F screw...makes it much easier to make the fine adjustments for better throttle response.
I would also not recommend running the oil level low...just don't over fill it. And change it often (motor). All JMO

 

We tossed the airbox mainly because it made access for maintenance easier. We added an extra catch can for the frame vent. We also ran the gearbox vent hose to the catch can. Our gearbox lube tends to find it's own level and spit the rest out of the vent. Better into a catch can than onto the rear tire.

 

Hotfoot, Scott here. I will be doing a valve clesrance check and will get you no carb heat shield pics for reference as well as the fairing upper off for the tank vent bottle hose routing. I have both factory manuls and will scan info to pdf fileds for you if you wish.

 

Wow, you guys are a very helpful, thanks so much! Scott - I have the service manual, in both hard copy and pdf, but that's all. If you have an owner's manual or something else that has additional info in it, I certainly would be interested in a pdf of it! I appreciate you willingness to take some phtoos, too, that is great.

For sure the heat shield/airbox is in the way when it comes to maintenance, getting rid of that sounds appealing.

Do you guys do anything to protect the air intake from sucking in dirt or debris? One mechanic that looked at the bike (I am still looking for the right person to work on/maintain this bike!) was shocked that there was no filter or screen over it and recommended covering it with a stocking or something. But I haven't heard that from anyone else and I hate to do anything to interfere with the airflow.

 

Tdub has forgotten more stuff on these than I will know. I would follow his advice on the oil. I incorrectly thought he was the guy that told me to run it in the low range of the dipstick, oh well.

Would have been fun to try the manifold flip on the track or dyno, do you remember how much it helped?

 

I have the complete parts manual from Moriwaki with good illustrations of everything. On the air intake ours is open as almost every other one I have seen. On an asphalt race track its not too big of a deal I guess. There is always the potential for large debris to get sucked in there. There always are smaller particle bits getting in. The evidence can be seen in the valve seat pitting when the top end is apart. In a crash we filled one with sand at Roebling, luckily the throttle slide was closed before the bike went in. You can run a paper or foam pod filter but depending on the fuel air mixture now you may have to re-jet for it.

I may be in the LA area soon, I would be happy to look it over for you. Everyone answering this thread has had to become a tech on these amazing little bikes. All good people. KKling has a head filled with experience on anything Moriwaki. I don't know how much time he spends here but you may want to reach out to him also.

 

I have the complete parts manual from Moriwaki with good illustrations of everything. On the air intake ours is open as almost every other one I have seen. On an asphalt race track its not too big of a deal I guess. There is always the potential for large debris to get sucked in there. There always are smaller particle bits getting in. The evidence can be seen in the valve seat pitting when the top end is apart. In a crash we filled one with sand at Roebling, luckily the throttle slide was closed before the bike went in. You can run a paper or foam pod filter but depending on the fuel air mixture now you may have to re-jet for it.

I may be in the LA area soon, I would be happy to look it over for you. Everyone answering this thread has had to become a tech on these amazing little bikes. All good people. KKling has a head filled with experience on anything Moriwaki. I don't know how much time he spends here but you may want to reach out to him also.

 

By all means let me know when you are in town, if you are out at SOW I might be able to meet you out there. Yes, I have seen some pitting on the valve seat bit it doesn't seem like TOO much junk gets in there, so I think I'l stick with keeping it open.

I'll experiment with the oil levels, but in restrospect it does seem to be true that it does better with the oil level closer to the low mark than the high mark - otherwise it wants to spit oil. I'll start keeping a record on that, now that I know what to look for.

 

The transmission side oil level will seek its own level if overfilled. Be careful there if the transmission breather hose just vents overboard..the oil can find its way to the rear shock linkage and the rear tire. Have never had an issue with the engine sump side blowing excessive oil out into the frame rail trap or otherwise when filling to the top mark on the stick. Only a very small amount of oil and water from condensation should drain there. There is a reed valve and strainer in the case to inspect. Some have been known to break off and find their way in between the cam chain and sprocket for it in the bottom end. The results are not good. I`m not sure about the relationship between the oil level and the reed valve. Kerry told me once but I have forgotten. With the amount of blow-by you are getting I am wondering if your breather is restricted or if the piston and rings are getting worn.. pressurizing the crankcase too much. PM me your email address and I will scan some pictures to you.

 

I run ours at the high mark cold. It is slightly above that hot. No issues with oil from the crank vent. I'm probably giving up a tiny bit of HP to windage losses, but it holds so little oil that I want as much as possible.
And Scott, get some sleep. No internet at 3 in the morning!

 

no rest for the unemployed..

 

You are not....

 

Since I have all these experts here... anybody have a gearing recommendation for the Las Vegas track? Just ran it last weekend with 17/42 sprockets; in the big sweeper after the back straight (turn 5 or 6?), 5th gear wasn't really pulling but I was afraid I'd over-rev it if I downshifted to 4th. So I kept having to choose between going in WOT in 5th and having no drive through the turn or slowing down prior to the turn to downshift. Is there a max rpm where it would be reasonably safe to downshift into 4th? Am I right to worry that I will damage something if I downshift while near the top of 5th gear, or are those two gears too close together for it to be a problem?

 

Assuming you still have the stock motor the gear ratios between 4th and 5th is large drop in RPM.. (I hear). I might gear for the best straight line speed even if it means never using 5th gear. The r-spec motor has closer ratios between 4th and 5th. Nigel has been running the x-motor gear box for a long time. Perhaps he will chime in here..