Day One - New Project

[hodakamax]

Yay, NOS Model 93 VM2400 carb on the way, Should be here in a few days. Maybe I can get to the bottom of this mystery!

Max

[hodakamax]

A quick report. NOS carb installed. Still basically the same problem. Something bad is also happening. Even though I'm getting plenty of exhaust smoke when idling and it runs fine mid range, in between idle and mid range it begins to slow. It appears to actually be starting to seize. Either it has a bad air leak or the clearances are just too tight. Out of time for the day, time to come apart and inspect clearances and for air entry. Grrr.

Max

[Bullfrog]

Mayhaps too late, but what happens if you jury-rig a stock exhaust system on for a test run? Your custom exhaust has a wayeeeee long head pipe and I can't remember what else. (Though admittedly, I don't have ANY hypothesis as to why only bottom half of throttle would be thrown off.) Hmmmm, like the church lady says, "Never mind."
Ed

[hodakamax]

Ed, I'm beginning to think that it was too tight in the beginning. I never checked bore clearance as the Guy has done dozens of bores for me. Maybe it was dragging and I was just tuning for more oil. More throttle, more oil. Speculation at this point, I'll tear it down, get some measurements and get you a report soon! Scary, I hope my experimental exhaust is not the culprit!

Maxie

[hodakamax]

This gets even weirder. Piston skirt clearance is a snug .002". The pin clip was missing and the pin was starting to nibble on the transfer port. The question is, did it go flying while assembly and I thought it went in or did it leave out the exhaust port? Both scenarios seem unlikely. There are some dings inside the transfer port but they could have just tool marks while porting. The clip could have went in the transfer and been blown out on the down stroke and bounced out the exhaust. No marks on the piston neither scuffing or dings. I even put a light to the crankcase to see if it was hiding there and to check for damage--None. No major damage anywhere but how much clearance should the skirt have on it? .002 sounds a bit tight. I did find a stock clip that fit the piston.

Max

[dcooke007]

Max,
Snug .002 inch piston to bore clearance is to tight in my opinion. Especially with a cast iron cylinder. I prefer .0025 to .003 inch with the new Wiseco / Strictly Hodaka pistons.

I don't know if the orientation of the piston pin clip is in the same position it was when assembled. But, for me, I would not want either end of the clip close to the clip installation dimple, divot, slot...what ever it is called. Prefer to have the tab end of the clip at the bottom and the dimple completely bridged by the clip. Just should be less likely to exit the piston that way. Most of the time I will shorten the clip tab about 50 % to reduce the effects of inertia on the clip also.

Danny Cooke

[hodakamax]

Hey thanks Danny, This is the position of the remaining clip, maybe that was the problem.

[Bullfrog]

Ouch! A close look at both of the photos of the cylinder bore shows pretty heavy vertical wear marks both on the intake and exhaust sides. You've measured .002" clearance AFTER some quick rides and a whole lot of idling. It seems like it had to be about .000" to .0001" on assembly. I'm kind of worried that it may have to be bored to the next size, or that you'll be at .004" to .006" clearance after dressing out the visible gouges - of course it could run for a long time even with loose clearances. Bummer.
Ed

[hodakamax]

Hey Ed, The gouges aren't as bad as they appear and don't go all the way of the ring travel. They only appear to be a few percent as compared to say ring gap. I think all is well and I've increased the skirt clearance to a smooth .0025+ which should be better. I've also rotated the clip as Danny recommended. I was darn lucky the clip didn't snag on something as it left the engine. Back together soon!

Max

[hodakamax]

An update. When re-assembling the piston I replaced the missing clip with a conventional one with a tang. The Wiseco furnished clips had no tang and were really difficult to install. They were both seated against the ends of the pin and one would assume seated in the groove on the first assembly. The conventional clip would not seat without cutting off the tang completely, the clearance is that close. It's as if the pin is too long or the grooves are not far enough apart. This time the clips appeared to be seated with some tapping and the engine is re-assembled. A biblical type rain has been occurring along with lightning and power outages the last couple of days and I've not been able test ride. Looks to be a good week ahead!

Max

[Dale]

Max,
I had my first encounter with the new Wiseco piston cir-clips the other day and I too found them a challenge to install. I suspect that someone that does this on a regular basis would laugh at us as I am pretty sure there is a easy method. If so, would it hurt too much to include an installation tip on the cir-clip package?

In hopes of helping the next person that sees these for the first time... I found it best to use no tool to get them inserted. I grasped the clip between my thumb and index finger, opposite of the clip opening. I then pushed the clip straight into the piston, clip opening first. As it compressed and made it into the piston, I began working it sideways towards its home. Once it was close, I used the flat end of my needle nose pliers to push it into its groove.

It seems that these new clips are less likely to cause a problem than the older style with the tangs, but installation is certainly different! If anyone has more experience with these and has a better method, please speak up.
Dale

[MWL]

I had trouble with the Wiseco circlips on my 250. I bought this tool called the C-Clipper. Worked great.
Mike

[Bill2001]

BMW uses the tang-less wire clips. Dale's tool-less method is one that works, but can be tricky. The C-CLIPPER tool that MWL uses works very well. That little wire clip can be a PITA !!!

[hodakamax]

The Day One project is fighting me to the end. Today I decided the engine needs a pressure check and me without the equipment. I searched the shop and Hodaka shed and finally came up with enough stuff to at least rig one. A piece of aluminum plate was used to block the intake and I cut the valve stem from an old tube to use to charge the system with air. The exhaust was closed with a solid rubber disc in place of the exhaust gasket. I have an air brush and low volume regulator where you can set it at 6#s. I did have an old gauge and constructed a spigot from a cable TV connector. Most of the time was spent stopping all the leaks in my primitive device. Finally I did get it to hold enough air to squirt soapy water on everything. Wow, major head gasket leak. When resurfacing the cylinder top the grit was just a little too coarse and the gasket wasn't sealing. A touch up with a finer stone cured the problem and the engine finally passed the test. This was probably the cause of the jetting dilemma and I'll check it out with some test runs tomorrow hopefully!

Max

[Bill2001]

For my recent top-end refurb I borrowed a commercial leak tester and adapted it to the Hodaka. I then fab'd my own pressure tester. An intake blockoff plate contains a tire valve for pressurizing the engine with a tire hand pump, with a hose nipple and hose to an old 0-50psi fuel pressure gauge. Exhaust is blocked off with an expandable rubber plug for auto engine freeze plugs (Dorman), though a rubber stopper jammed into the exh port woud work. I concluded that a leak tester is a gopd routine service tool for 2-stroke maintenance.

[hodakamax]

The mystery continues on the Day One Project. Perhaps it is the long header pipe creating some major leanness between idle and 1/2 throttle. The cylinder seems to have the proper clearances but eventually begins to seize at about 1/3 throttle. Strangely it has a good mid range hit with lots of smoke . Yesterday I pressure checked the engine and found a severe head gasket leak and remedied that. I was sure that was the problem but in testing even with two different carbs the problem persists. Meanwhile it appears that it has ejected the piston pin clip yet again or at least it started a strange vibration. Max wasn't in the mood to spend yet another day to check and see what happened. For the moment the plan is to take it to a car/motorcycle show this weekend running or not. Grrrr.

Max

Her's some pix of the last fiasco. About 30 minutes running time. Strange deposits on the piston near the exhaust like burnt oil, hard to remove.

[Bill2001]

Yes, 2-strokes can be quirky. This is why I am getting instrumentation like an EGT meter. This way you have something physical to look at besides a seized piston. You can guess that it seems that this is happening because that may be present, but good readings narrow things down. In addition to EGT, there are also AFR (air-fuel ratio) gauges available.

[Dale]

Dang Max, I am feeling your pain. I wish I had more experience to offer on a situation like this... unfortunately I have none using pipes such as yours. I hate this for you. Deep breath time?

[Kels]

It's too bad, you don't talk to me.. I could help ya out...

[hodakamax]

Thanks Dale, You did actually at least make me laugh! I'm taking a deep breath and I've at least got the exterior ready for the show. I'm actually embarrassed about the whole thing, being an old Hodaka guy. This engine has been plagued from Day One so to speak. In theory this should all work and the whole concept revolves around the engine and exhaust both in performance and looks. Lengthening header pipes is not new nor the longer intake, both recommended by Harry Taylor. Weird. Then the piston losing a pin clip, twice maybe, is strange. I may wear different color R&L sox somedays but one never forgets to double check pin clips. As you say, time to take a deep breath!

Thanks for your sympathy, it did make me feel better!

Max

[dcooke007]

I looked at my Wiseco piston and the piston pin circlips are a little different than the ones you are using. Did not occur to me before.

[hodakamax]

Hey Danny, the clip that came out was like yours, I had a Hodaka one in the picture that I was trying. It would not seat without cutting the tang completely off. I'm thinking that the pin is too long making the clips hard to seat. AZ Shorty just contacted me mentioning that the clips probably shouldn't make contact with the pin. As the pin heats up and gets longer it's probably pushing one of the clips out of the groove. Sounds reasonable to me. I'll check with Paul and see if this could be a problem. It came with the wrong rings and perhaps the wrong pin. Aggravating for sure. (Not even counting the seizure problem.) Grrr.

Thanks!

Max

[dcooke007]

Max,
Ok , I know I have senior moments....thought you might also.

If the pin is a bit too long you can carefully grind one end and gain some clearence.

[hodakamax]

Strange that there are two problems and they could be related. Maybe as the pin expands against the clips it could begin to distort the piston in a new tight bore. It wouldn't take much. Something strange is happening for sure. All speculation at this point but I can only solve one problem at a time. Maybe it's just one problem I'm up against.

Max

[DGardner]

I checked the wire OD on a hodaka clip and it is .048 and a weisco clip is .038......so it may not be sitting down in the groove.