Will I get my 100 ready in time for Taupo?

[jasonu]

Blah blah...So what are the known faults?

It's a Honda.

[F5 Dave]

NoNo - that's been filed off the side cover. Its been replaced (picture can't really pick it up) with some other letters made from stickers & painted over (need to find ones that have more thickness for the next cases). If you look closely it says P I S S O F F. It was hilarious 16 years ago, but no one has noticed it yet.

[koba]

NoNo - that's been filed off the side cover. Its been replaced (picture can't really pick it up) with some other letters made from stickers & painted over (need to find ones that have more thickness for the next cases). If you look closely it says P I S S O F F. It was hilarious 16 years ago, but no one has noticed it yet.

That is quite spooky, I'll explain why sometime.

[F5 Dave]

Well more testing & started to look a bit promising. Seems to have picked up a chunk of midrange, or more correctly the power starts earlier in the revrange & follows the same curve, but had another 1.7 at 10k. but then seems to dip & fall & then falter at 12 which was previously peak. So 10 is now peak. hmmm.

Many timing & jetting changes with PJ mods mixed in. Hard to get consistent readings & rev trace is falling over. Is this a return of the suspect ignition issuesI was having before with the RS ign? Maybe I need to try the RM back on. & as time goes on I notice the gap in the reed as I idly gaze in the inlet. Ahh crap. Wonder how much that is affecting it?

Some anecdotal response is that broken or chipped reeds will make it hard to start but shouldn't be an issue after that. my own experience on the H was it would start fine but have a misfire up top that would have me chasing ign. The MB starts fine.

So my steel reeds are back at home. Waste of time continuing & I don't know when it chipped & if it got worse. Later I see every reed side is got Damage appearing. So this Polini reed material isn't much chop for high revving engines it seems.

Where's the concrete?

[speedpro]

The reeds aren't rubbing on the side of the intake port or is there possibly a round corner of the port that the reeds are opening against? Sometimes even with stock reed stops the reeds extend far enough past them that when fitted into another motor unless you take a lot of care they can still tap the edges/corners of the port. Not saying you haven't been careful, really

[F5 Dave]

you know I was having that very thought this morning whilst shaving. There is no inlet port as such as it's into the cases & I though everything was clear but I will check again.

[F5 Dave]

So back on the dyno, I'll have a look at those reeds later. So yeah more power with steel reeds that aren't chipped. Few jet changes, nah likes the 300 & that's it. Still can't get a proper rev trace, just disappears at 10 where it gets within sight of 20 then makes a bit of a weird noise, half like its stuttering, but half like its slipping. Always just after 10. If I run up from real low revs sometimes it looks like it will pull through.

Inconsistent readings. Must try RM ign. Either that or the RGV carb which is a pain is just loading up some times. Try different power jet arrangement, nah 18 or 19hp.

So try an all gears run which I do every session to get a reality check & see if power falls off in higher gears. Balls up the changing a bit, but through the gears ; 15hp (1st always hard to read) 18, 18, 18, 23.5, 18. Hold on a sec. try that again. 22, 22, 22, 22, etc.

ok so spinning it out through the gears vs one run is either not flooding it due to high continuous airflow, or it is keeping a stator coil charged up a bit higher. I had tested the coil in the environmental oven at work & it seemed consistent values, but the CDIs on these early RS were known for throwing wobblies.

ok so there is potential there, just have to release it. When I started this engine 16 (17) years ago I was aiming mid 20s which was as high as anyone had managed. If the cases weren't leaking I think I'd be there.

ok so home & lets look at the reeds. Hmm, oops, yep, they rub. Another thing I overloked all that time ago, I changed to a wider reedblock 1/2 way through & can't have opened it up just enough. So what to do? If one remembers I glued these cases together in an (unsuccessful) attempt to stop them leaking. OK well maybe close the stops a mm. & make a reedblock spacer to pull the cage out 6mm. Carb now just rests against the shock, can go no further. But it isn't enough as the inlet is rounded at the corners. ok, fuk it, stuff a hankie in with some grease & dremel it. Not pretty but no option. Didn't get too much ally dust in there. . .

I need to finish these new cases. Wish I had another 32ish mm carb that had as steep a downdraft as the RGV ones, I don't trust these carbs. straight carb would never run on this inlet.

[Grumph]

Dellorto's will run happily at 42 degree downdraft.....

[husaberg]

So back on the dyno,
I need to finish these new cases. Wish I had another 32ish mm carb that had as steep a downdraft as the RGV ones, I don't trust these carbs. straight carb would never run on this inlet.

NSR250 its from a Honda. Also Honda own Keihin. Honda used various sizes. Honda also measure at the venturi MC16 =28 MC18=32mm. Do you need a Honda carb for your Honda framed Honda engined bucket. Other than that there were 2 styles of mikuni for the RGV but what carb did the 3xv Yam have the v twin i am not sure but it was a Powerjet one?

Dellorto's will run happily at 42 degree downdraft.....

Good to know. i supose it has because they work sideways on the Aprilia disk valve as well. I never thought about that before.

[F5 Dave]

Thanks, A mate has some magnesium Dellortos, but I'm not prepared to go buy another set of jets. I have Keihin & Mikuni already. Problem with the Honda carbs is they run that silly double cable setup & the pulley is too tall, the shock sits right above & it is currently touching. I have a stack of 28s, but they are a bit small for what I want. Can take them out a mm.

[Grumph]

[QUOTE=husaberg;1130232907)


Good to know. i supose it has because they work sideways on the Aprilia disk valve as well. I never thought about that before.[/QUOTE]

Nah, it's basic carb layout. If the idle/slow run circuits are on the engine side of the carb,(most Mikuni, some Keihin) then at some point you're going to get fuel dribbling permanently from those circuits when you tilt the carb.

Dellorto's in particular have those circuits on the air intake side and can be used at very steep downdrafts. roundslide Mikunis won't take more than about 15 degrees.....

Mmmm Magnesium,,,,,does he want to sell ?

[F5 Dave]

I could ask him, they're off his Rotax tandem disc valve, has Miks now as suits shorter NZ tracks. Not that's its had much use lately.. .

[F5 Dave]

I've seen some people us round Miks at about 30 degs with no dramas. But any time I've tried more than the error margin of a spirit level (ok maybe an exageration) they spew no matter how you adjust them.

[diesel pig]

I would not usually offer carb tuning advice because I am usually asking for it. But since you are using a downdraught 32mm mikuni off a RGV which is same carb I have been mucking about with for last couple of days. While doing the full bell maunal tune up when offering up a foreign carb to a new motor after finaling to get anywhere with a quick and easy "find the right main jet and fiddle with the needle til works kind of" tune. I found when doing the needle jet test the one where you run the carb with out the main jet and if it is the right size the motor should flood badly at half throttle that not only did it keep running it would except full throttle and seemed more like a carb with one or two size too big main jet. After making the needle jet bigger and finding a needle that would work with it transformed the tuning of the motor and it can now take snap openings and run clean thou the mid-range. So even thou they are not same motors they are case reed 100's with the same carbs so maybe if you have not already check it it maybe some thing worth doing?

[F5 Dave]

Thanks Neil. I pretty much remember doing that back in the day & is one of the first things I do, but heck who knows, it wasn't running well then so its worth retrying - so I will for the sake of it.

Presumably you have blocked off the two idle mixture bleeds on the front of the carb (though I think maybe Jap models had them on VJ21, whereas all VJ22 did).