exhaust plugged

[old smokey]

I'm still working on getting the Honda MB5 running properly. My next thought is that the exhaust pipe is partially plugged. I'll probably pull it off this weekend. Any suggestions on how best to clean it if that is the problem? Some form of a chemical cleaner?
It's difficult to start cold. Most times it will rev pretty well in first gear, but as I shift up it won't rev smoothly or very high (and gets worse when going uphill vs downhill). Compression is about 105 psi.

[OldSwartout]

Oven cleaner helps loosen and soften carbon, but DON'T use it on aluminum.  Scraping with a screwdriver or other instrument works pretty well on areas you can get too.  You can also use a torch to burn it off of parts that are hidden and/or not chromed or painted; i.e., removable exhaust baffles.  Check your exhaust port in addition to the exhaust pipe.  I've scraped out an exhaust port with the engine still together - try to use a bent stiff wire or something with a hook to pull most of it outward.  The carbon buildup that accumulates in an exhaust port is soft enough that it won't damage internal parts if you leave some pieces in there, although they might foul a plug before they get blown out.

[Richard Clark BS parts]

I agree with Karl on carbon removal. I hate to say, but your problem might be, low compression, In my
opinion 105 is too low to run correctly.

What do other guys think

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Richard Clark




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[old smokey]

I removed the exhaust pipe. Very easy. No problems visible with that system. It certainly won't ever rust out from the inside. An unofficial site someone has for MB5's says 105 psi is his personal minimum compression it would take to run. He thought it should be as high as 185 psi.
A more official site says they have 7.6 to 1 compression ratio.
But what I saw while the exhaust pipe was off makes me wonder. I've never seen rings on a piston while it's still in the bore, but to me it looked like the rings are smeared into the landings of the piston. I would expect a miniscule gap between the rings and piston. Maybe I'll be tearing the top end off. If there is any damage to the cylinder or piston, maybe I can splurge for a 70cc upgrade.

[OldSwartout]

maybe I can splurge for a 70cc upgrade.

That should make it run better!!!  This thread was just to come up with justification for the 70cc kit, right?   

[old smokey]

Friday was when I saw the smeared rings. Then I ran it w/o the exhaust core in and it ran no differently. So Saturday I tore the cylinder off. As I was doing that, the rings looked normal. But the gasket on the bottom of the cylinder tore so I'll have to replace that before re-assembling it. I don't know if the smeared ring material came off Friday and made no difference in running or it knocked loose during tear down. I'll try to get another compression reading before the next start attempt. Otherwise, I was kinda hoping to justify a 70 cc upgrade...

[stone Man]

So Smokey, anything new to report?

As for exhaust cleaning, my pipes were pretty oily so this winter when I was doing some overall cleanup, I cleaned the inside with kerosene. I pulled the baffels, cleaned them with a wire brush, then turned a couple wood plugs on my wood lathe for each end of the pipe. Poured a pint or two of kerosene in, plugged that end and played bartender/mix master shaking the kerosene in the pipe. Well, the gunk sloshed out when done so repeated and more junk came out.

I doubt this will dissolve built up carbon, but for gunky oil removal, worked great.

[old smokey]

Lessons learned to date: if you ever question a spark plug, just replace it. I compared the one from the MB5 to the 350 GTR many weeks ago and they had the same visible spark so I put the MB5 back in (both use NGK BH8RS). Saturday I caught the MB5 when the plug decided to not work, I knew something was up when even rolling downhill wouldn't get it to fire. Temporarily swapped in a GTR plug. Monday got new plugs for both bikes at AutoZone. Today heard back from a shop in Indiana specializing in MB5s. He told me to check a small passage in the carb. I think that one is okay, but difficult to check with a small wire because of bends in the casting passages. But - as I removed the float bowl there was the main jet body rolling around in the bottom. Oh yea, I was the last one to work on that. Guess I'll worry less about stripping brass threads than having it come loose....
Hopefully a test tomorrow will produce some long awaited results. Although the specialist did say that having 105 psi compression might be a problem too. Maybe a 70cc upgrade won't be too far off anyway, but it should do better than it has so far. And we had fresh snow on the ground this morning when I woke up!!!

[old smokey]

Finally got some results that I wanted. The MB5 specialty shop in Indiana told me there was a small hole in the carb that goes from the venturi throat to the float bowl side of the carb. I finally got a small hole broken thru it and put it back together. With a few kicks, it started and ran smoothly. Maybe a little tweaking to the idle speed or something, but now I know it's worth getting the title and plates for it and go beyond my neighborhood. And then I can get more miles on it and see if the probable low compression becomes an issue. All it really needed thus far was a new spark plug and the carb cleaned. Now to wait for warmer weather.

[stone Man]

Hey, Smokey, looks like you're on your way now. Congratulations!

Is your bike untitled? So is mine and need to do something about that. I know getting retitled varies from state to state, but wondering what you are planning? Here in Ohio, requires going to court, which is at least a couple hundred bucks before you register and get tags. There are so many untitled, good running bikes out there, you'd think that after a certain age, the state would make it easier.

Any body else have experience with this? Suggestions?

[Dave K]

In my county of Ohio, Auglaize, they told me there is no way to get a title unless you can produce the old title. There is no such thing anymore as a salvage title. I was told that, this past Nov. or Dec., that to even have it and part it out, can be construed as operating a chop shop and land you in jail. I am sure some counties are more friendly on this topic than this county. I did stand in the office as the deputy called the state to see what could be done. Ohio is telling me, that if it is legal, it has a title. I asked about a lost title. They said the owner can apply for a lost title replacement and the ser. no. will come up as having been owned by him. More questions were placed and I was told it is the sellers problem to provide a title with a motor vehichle, if it is legal. So don't go to jail for the seller who can't produce a title. 2-3 yrs. ago, you could get a salvage title, I did, for an bike left behind when the owners were foreclosed upon. I was told NO MORE, is that going to happen.

[old smokey]

My MB5 did come with a title, although it was signed over by some prior owner in 2001. I don't remember if I really compared the title VIN number to the bike, but I don't think it will disagree. My dad has an older Honda CB650 that he bought at least 15 years ago and only got a bill of sale. Way back then he was told by his county DMV that all he has to do is have the sherrif verify the numbers and then can get a new title. I was kinda interested in getting that bike running too, but I told him I'm not touching it until he gets a title. That would be in Indiana.
Not sure when I'll get the title. Now my employer wants us to work this Friday and next one too. I suppose I could go during lunch and stay late to make up the time...

[old smokey]

The MB5 now has a title and plate. My wife's 50cc Yamaha Vino definitely beats me off the line, but I eventually catch her and have 3-4 mph extra top end. She doesn't appreciate the smell of 2 stroke oil so I'm supposed to stay behind her. It
looks like gas prices are starting to creep upwards again so it might be used for commuting to work once it's warm enough in the mornings.

[stone Man]

At the moment, my son and his lady friend are trying a titling service in Nevada, I believe. I read about it on the SOHC/4 Forum. The deal is, for a fee they will do a VIN number check and if doesn't come up dirty, they will title the bike in that state in their name and sell your bike back to you, at which time you go the DMV (Ohio in this case) and get the title transferred. Sounds good on paper, we'll see how it works in reality. The guys who posted about it on the other forum had some luck with it. I'll post again to let you know how it turns out. Should know in a couple weeks.

It's so dumb. You'd think that after a certain age, a bike that doesn't come up stolen ought to be able to get a title. Seems like every other vintage bike on craigs list has no title and they can't all be stolen. I've also heard that you can go to court (Common Pleas?) in Ohio and make your case to a judge who can authorize a title to be issued, but I understand that process can cost up to $300 in court fees. My son's BS 350 came from a guy he knows who owned a building. Couple years back he had to evict the tenant. The tenant left behind three old bikes, including the 'stone and lots of other junk. My son got it in exchange for a little work. Now I know in the case of an eviction the tenant must remove his property within a specified time or else it becomes the property of the landlord to dispose of as he sees fit. (Don't ask me how I know this.) 

[rocketman]

Its true that individual states seem to have thier own set of regulations to determine when and why any motor vehichle should be eligible to re-title. The Nevada and New Hampshire title services seem to work real well for most every state that I am aware of. However,shop around your local title service companies. They know things we don't and a good one keeps up with the current laws and changes. They can be pretty quick sometimes and pretty reasonable cost wise to. Also think about this,contact relatives and trusted friends in other states. Their laws,etc.,may be different than yours. Once clear title is issued by any state,it is usually respected by the others. Taxes and fees can accumulate from transfers,adding to the overall cost,but where theres a will...     Mark.                                 

[old smokey]

If I could be 100% certain of getting titles for bikes sold with bill of sale only, I'd probably be sleeping with a garage full of bikes because my wife would justifiably kick me out of the house. I've seen a couple interesting bikes on eBay from a salvage shop in Appleton and their ads always say "this bike will never be given a Wisconsin title." Or there's the local Honda 650 Turbo at Rerun Motorcycle shop.....

The MB5 has nearly 200 new miles with me at the controls. With no comparison of older 50cc bikes, I'd say it does as well as can be expected. You have to downshift on moderate hills or headwinds of 10 mph or more. The next fill-up will give me an idea of what the mpg is. I'd guess a flat road with calm conditions would probably give a top speed of 43-45 mph. But I rarely get either around here so far. I usually hold about 8500 rpm's!!! Attack of the killer bee 

I picked up a gallon of dairy product for removing Milkstone as recommended by the owner at Rerun. If a wine cork plugs the fuel petcock hole on the 350 GTR tank, I might be scouring rust this Memorial Day weekend. This stuff has a 56% phosphoric acid solution by volume.

[old smokey]

Today was the first fill-up for normal operating conditions. Sweet - it got 80 mpg. And gas has jumped up to $2.42 at the nearby Citgo. Looks like the MB5 will get plenty of use for work commuting when the weather permits. The oddball layout of the gas tank does leave a little to be desired when getting down near the reserve level. On moderate hills it seems to let most of the gas go underneath the seat portion and not keep the float bowl full.
Oh, I keep forgetting to mention that the MB5 has a Bridgestone tire on the front. I see that the beautiful GTR (on youtube I think?) has Bridgestone Spitfire tires on it.

[billmo]

Just wanted to let you know that the 650 Turbo is no longer at Rerun's, it's in my basement.  I saw it had 8 miles on it and couldn't resist.  It's one of the bikes American Honda donated to a tech school and is not supposed to be titled or driven but I'm not sure I can hold off.  They are supposed to be wicked fun to drive.  The MB5 sounds like a cool ride.  It might not be the fastest bike on the road but it's got character.