'72 Rat 93B carb issue

[Scotty Rat]

I've been MIA for some time in the Hodaka scene lately, though still racing VMX on some other brands since retiring the "Rat". 72 93B Rat
Question: This issue has had me stumped for years, stock carb, after laying it down, or a trip over the bars, it floods (loads up) and refuses to "clear out". Takes 3 to 5 minutes, throttle held wide open, throttle held in a variety of positions 3/4 ect Same results, the pack races by for the second time and I stand there waiting.... Any ideas why? Some one suggested replacing both the needle and needle jet? Engine is still somewhat fresh after George Cone rebuild, carb has been gone thru multiple times. Carb still has the stock vent set-up. Thanks, Scotty: Yea, A few races this year in the picture! 100cc series starting back up in Florida.

[matt glascock]

When the bike loads up like that, are you shutting off the petcocks before you clear the engine? That happened to me with my first '72 Super Rat. With the fuel to the carb shut off, it would take 15 to 20 seconds to clear the engine. I ended up tapping a petcock into the float bowl to make it a faster process. Be sure to run a vent tube from the outlet of the petcock out the bottom of the frame.

[socalhodaka]

Matt, can you post a photo of that setup
Kelly

[Scotty Rat]

I'm closing the petcocks, but it still takes minutes, not seconds to clear out? Bike runs great till the crash! I'm running the next size up pilot jet, it helps in the sandy corners in FLA.

[Bill2001]

New 2-stroke owner here, pardon me for breaking in. I understand what "loading up" is, but what are the characteristics of loading up? What is the engine doing, and what causes it?

"TIA"

[matt glascock]

Kelly, I would love nothing more than to show you a detail pic of the carb mod but that would require asking the foreman of the Black Hawk County land fill to show me which stratum was filled in 1979 as that is it's current residence. Bought used in 1976 for $100, that '72 SR had the wheels raced off it for three years at which time the frame was more weld than frame and it was subsequently tossed in the dumpster of the filling station where I worked at the time. By that time I was running RMs, then KTMs and that was it for me and Hodaka for decades. Sad and oft-repeated story. I'd really like that bike back. Spilled milk. Anyway, here's the mod as I can recall. The bike was ported for reed valve induction and was running a 28mm carb. I can't remember if it was a Mikuni, Bing, of Amal as I was using all of those at one time or another back then. What I can recall is that it had a sediment cup with a removable nut that was flat on the outside and concave internally. I know I've seen this set-up recently on Mikunis. Anyway, it was there where a hole was bored and tapped to accept a generic petcock which was further supported internally with a thin nut from, get this, a microphone stand. The redundant threaded portion of the petcock was ground off to keep a low profile and avoid interfering with the main jet. A fuel line then drained the outlet of the petcock through the bottom of the frame to avoid fuel dump onto of into a hot motor. I also recall a cupped fiber gasket with one flat side and one convex side (it was probably a faucet washer) to conform to the concave inner surface of the sediment cup drain/main jet access nut used internally and a standard petcock gasket on the outer side. I'll try to cobble together a facsimile and get a photo together to illustrate.

[dirty_rat]

Hey Scotty, welcome back. So, you are saying that Sunshine State Vintage MX is going to have a 100 cc class this coming year? I looked on the site and didn't see it listed. I don't remember your bike loading up at any of the races I was at. Is that a new development?

[Scotty Rat]

Dirty, it only loads up after I crash or slide out, or get T-boned. It has done this forever, guess I've kept the rubber side down most of the time. Take 3 to 5 minutes to clear out? Something is wrong?? What do you think? You have my ph#, get an idea call me.
100cc class was on the list for this year? Got scrubbed? I'll check Sunday at the Year End Awards in Ocala.

[Bullfrog]

Since being a bit rich can seriously increase the chance of loading up, I have to ask about the one step richer than stock pilot jet because, "it helps in the sandy corners . . ." I kind of don't "get" that. The right pilot jet is the right pilot jet whether the corners are muddy, rocky, sandy or asphalt. So, when you follow the procedure for tuning in the pilot jet/pilot air screw (recently mentioned on about page 22 or so on Maxie's project thread), what pilot air screw setting do you end up with?

Ed

[Scotty Rat]

ED, Just checked air screw: 1 1/4 turns out. The pilot jet was something Bill Cook & I discussed some years back when I was racing the 100cc MX series in Florida. Personally I believe it helped. I was only using the "Rat" for MX racing. No XC or trails. I believe I went up 1 size to a 32 (I believe, I'd have to disassemble). The loading issue I started this thread about only happens after the bike has been dumped over on it's side. Not very often as Dirty Rat questioned, but do-do happens at times. (side swiped, t-boned, rider goes down right in front of you and becomes a non planned jump ect.. 52 motos in one season alone. Cracked the frame on the Gravity cavity @ HardRock led to the Bike's semi-retirement. Still racing my 250 Elsinore & Penton 250HS on a regular basis.
The length of time to clear out, petcock off, throttle wide open is the question? Why 3 to 5 minutes to clear? B8HS plug, 32 to 1 Golden Spectro. Non eth fuel, points ignition. 85 to 95 + degree race time temps. 99.999% of the race time, the bike runs great.
"A bit rich" , I'm one that goes by the saying, spark plugs are cheap, engines ain't. So yea, I like 'em tad rich.
Scott "Rat"

[Bullfrog]

OK. When the pilot jet dials in at 1 1/4 turns out . . . that's the right pilot jet. That clears up that question.

Which leads us back to float system operation. Hmmm, you don't report any weeping, over-flow problems - so how about float level setting? Float arms should be parallel to the float bowl gasket surface (carb up-side down) with only the weight of the floats bearing on the float valve.

. . . and then going a little farther afield with questions. I may have missed it but this is a piston port engine right? Has the porting been changed in any way? Stock intake manifold? Other changes between the air cleaner and the silencer from stock?

Ed
PS: In my own experience, a 30 second clean out from loading up feels like just shy of an hour or so . . . but if guys do actually complete a lap while you are sitting there, then the 3 - 5 minute has got to be accurate . . . and does seem longer than normal.

[Scotty Rat]

Ed,
Float level checked and double checked, George Cone rebuild, I don't believe he gets carried away porting. OEM Stock air cleaner set-up, Uni foam.

Exhaust is a Bassani that was installed at the time of sale by the dealer. I didn't purchase this bike new, a friend who lived next door bought her tho I rode this bike the day he picked her up. That's how I know about the exhaust. I was racing Pentons back then also.

Bassani pipe issue? Runs like a scolded "Rat"?

Thanks for your time,

Scotty

[Bullfrog]

Well dang Scotty, you keep giving good and reasonable answers which offer no clue to me as to why it takes so long for your scoot to clean out after loading up. So at this point, all I've got left is the concept that being rich makes loading-up more likely . . . and you report being purposefully slightly rich . . .

ALTHOUGH, lets not forget the carb vanes which have been mentioned. They worked wonders on the Combat Wombat for virtually eliminating loading-up. I highly recommend them.
Ed

[Bill2001]

One idea: verify that the engine is indeed loading up. I have no idea how to "verify". Something else might be mimicing the "loading up". One thing I have learnwd early-on about 2-strokes is that carburetion is critical and may be tricky.