Amazing. They started making the Doohan replica helmets again....it's not quite accurate but it's good enough....


Top: My original from the 1990's complete with 1993 Snetterton scrutineering sticker...


"Raced" is probably an exaggeration...more like I rode this Rent-a-Racer LC around Snetterton and did a great imitation of a rolling chicane spoiling everyone's lines...I wasn't dead last in any race but was challenging for it!

You show that MC18 all the love, and it just keeps kicking you in the balls!

I admire your dedication! 🤣🤣
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At last I finally got round to replacing the mechanical seal. I wanted to get it exactly right and so spoilt myself with getting some OEM Honda tools to make sure it went right.

Per the Service Manual


Got most of it...


Bearing goes in first.....so it got placed in the freezer for a bit to make it smaller and I heated up the casing to make it's prospective home a little larger....we're talking in mini micro amounts here...but I think it helps...


This bit, called the 'pilot' goes on the end of the driver handle...and centers the bearing...


and this outer part takes care of the outer edge...








Next flip the case over to the oil seal....not the greatest pic but you should see that the flat side faces out...


used a tiny tiny smear of Red rubber Grease to ensure it slipped into its permanent home with ease also but a bit on the inner ring of the oil seal where the water pump shaft will soon slide plunge through...


then this tool comes out to tap in the mechanical seal without any distortion....



mechanical seal has it's own strip of lubricant/sealant....


sits on here...


here comes the tool at the end of the driver handle...


..tap...tap...and it's in...


with all the bits assembled into the case, it's time to put it back on the engine...gasket first....it's still in good nick and a thin smear of rr grease is enough to hold it in place...


water pump shaft/gear goes into the motor....


but don't forget the washer....#16...which goes in FIRST...


Doesn't do any harm to put in a new waterpump housing o-ring...i just happened to have an extra...so I did it...



made sure that both the kickstart oil seal and the water pump oil seals were lubricated, slid on the case and torqued it up...


this is how this is inserted into the impeller...that white ceramic side meets with the mechacnical seal...some pundits say to put a bit of coolant on it so it's not completely dry when it starts up...seems a little pointless but did it anyway...make sure you place the washer in (#17 on the above parts list) within the ceramic spacer


this is a pic during disassembly to remind me about the washer...the impeller spins onto the water pump shaft and then it's a lot of boring reassembly of plumbing and bolting up the water pump casing ideally with a new gasket but mine was still good considering it was only on a few months....and then refilling the coolant....


a fresh washer on the sump bolt is always a good practice...


and my oil of choice is Motul Transoil 10w-30 almost certainly due to good advice acquired from this forum.


And long story short.....been running it around for about 200 klicks and it's dry as a bone underneath.....overall running good but at quarter throttle annoyingly very burbly and I've yet to focus on that ....it must be right where it's transitioning carb circuits so I have to study which variable I can..well...vary...

Note I've left off the inner piece of the bottom fairing to give me access to the front plug...always checking it's colour.

Slowly getting there! Great addition for the recent water pump questions too.

Made some changes to my model after looking at your photos too!




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Andy.
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Brilliant! Website always moving forward.

Still having a hard time getting the front cylinder to fire as well as the rear. Bike really takes off when it comes to the power band but very burbly below it. Non-scientific test: stadning still and revving it Holding my gloved hand over the exhaust for the rear cylinder the heat is noticeably higher than that of the front cylinder and there's quite a punch of gas...I can't hold it there for very long before it get's too hot.....for the front cylinder it's tepid- could hold it all day and the pressure isn't that great even though both cylinders gave equal compression readings.

I'm just wondering is this a sign of a weak or a rich mixture or there's no way of telling...could be anything?

Running V2 race gas...front is on the right, rear is on the left.

Honestly, first thing I always say is, put it back to (relatively) stock!

For a start, I'd be putting BR9ECM plugs back in it. (Or are those the Denso equivalent? I've never used them.) Second, "race fuel" really might not be helping as you may be expecting. I've never used "V2", so can't comment on that specifically, but I can tell you that (a) I'd never run AVGAS in anything but a full F3, and (b) the last time we set up an NSR to run on Elf MITS-46 "race UL/fuel" (an NSR500V), it was shite! The client immediately lost 15hp, and required a completely different setup. The powerband became the proverbial light switch too!

What's the best regular pump fuel you can get where you are?
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Much appreciate this feedback- that's fascinating about the NSR500.

When I first tried the 'race' fuel I thought I felt a major difference but I think I was kidding myself.

The best I can get is 93 octane and we are lucky enough to have a non-ethanol supplier nearby so I always get that. Those plugs are NGK 3520 BR8ECMIX Iridium IX Spark Plugs but I have yer normal ones too. I'll dig them out.

Also I'm running without the top of the filter box but I have the unaltered OEM top AND a four holer.

The problem is we've found every setup responds differently, hence why I don't let people discuss specific settings. I do remember numerous occasions where "no lid" performed significantly worse than with a lid though, which kind of contradicts how well (a) my MC21/NSR-WORLD tune works with Ramair pod filters, (b) the F3, and (c) HRC SP runs so well with just the minimal thin plastic carb shield fitted! Our NSR-WORLD tune does include crankcase work though, but the SP tunes don't, and they work well with just the shield and open carbs!

I'm not entirely convinced by those BR9ECMIX plugs. I hold my hand up, and say I don't know about the properties of iridium plugs, but I've often wondered if they are suitable for an ECU effectively designed 40 years ago, and if they "need" more juice than an ageing PGM can supply?! I remember Matt@TYGA telling me how, even though part of the MC28 race kit, they often even struggled with poor signal when using the R5300A plugs with the PGM-IV. We've never however, had any problems with the BR9ECMs.

My little snippet would be "stock NSRs tend to run inherently rich". As standard, they need to work "out-of-the-crate" in all kinds of climates and (within reason) altitudes, on not always the best fuel! Opening the airbox up, and delimiting the ignition affects jetting much less than you may suspect. Almost as if they're pre-prepared for delimiting! You may be looking at closer to stock settings than you think. It's also well worth asking TYGA (if you haven't already) if they recommend main jet sizes with their system. (When I bought my Ethos chambers and KISS delimiter from Japan, Ethos also supplied a pair of main jets -- I can't say what size, as it's irrelevant to your situation. Maybe TYGA have a preferred size too though?)

Not sure if any of that waffle helps, or just confuses things even more? Basically, I'd recommend getting things closer to stock, rather than trying to make a slight mis-match work, and then restart modifications.

At least you know the PGM and RC Valve is good now.
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All of that information is MUCH appreciated. Thank you!

So I took off the tank, drained the V2 race fuel and put in some brand new NGK BR9ECM's


I had a gut feeling about the RC Valves and in danger of adding to many variables to the test, took off the side fairing to check the power valves adjustment being careful to check in on exactly how to do it (thank you Andy) AND catching up on MotoGP Practice


started it up with the fuel left in the bowls...let it rev to 2000k and killed it when the RC Valve Pulley moved to the HI point.....note these don't have the pointer that the original has but you can tell where it should be.


they were slightly out but now are spot on...


I put on the four holer airbox lid and double checked the carbs are sync'd ok. looks good.


Took it out....rear cylinder acting normal- front again not happy. Felt like it was running on 1 cylinder all the way didn't reach any exciting power band. Quick u-turn home. Took off the tank and removed the airbox lid...simply because it was the easiest change to make.


It was MUCH better but again didn't reach power band.....front cylinder still practically dead. OK- just to be sure may I ask: which carb takes care of which cylinder. I think it's LEFT carb for the FRONT...am I right?

I think it was a mistake to adjust the power valves in all this- so going to double check those again and then I'm going to take the carbs off and I may send them to MuttsNutts to give them a good clean and going over- partly because it will give me a break from the NSR and allow me to fix some of my broken bikes of which there are TOO MANY. When I get them back I will return to standard jetting. who knows. that might be the answer. FIRST will attempt to talk to TYGA again about jetting. I've tried before but got no response. Since then however I think I have a more direct contact.

Couldn't resist pulling the carbs for a look see myself instead of sending to UK.
Confirmed they are the correct ones.


I got excited thinking that the slow jets look completely different, but I've been down this road before, they are supposed to be both 38's..


they ARE 38's...except the 38 for #2 (rear) is a 38S


original jets back in 130 for #1 132 for #2


Checked the float height....13mm is as close as i can get it.

Only other thing I discovered is that the power jets were in the wrong carbs. Website here says it should be #1 should have a 75 and #2 a 70 but it was the other way round so switched them- but is that correct? #2 usually needs more fuel as it gets hotter. Wonder it it will make that much difference- then I just remembered- need some electronics to have the power jets work....so they are non-op

Phone died so no more pics for the moment...

Left carb, as you're sitting on the bike, feeds the left cylinder. Check the layout of the exhausts... I can't remember if the TYGAs cross over like the OEM MC18 pipes, so the exhaust pulses are on opposite sides?

The power jets aren't electronically controlled. The higher the RPM, the more the "draw" on them, so they are effectively progressive. This is why the HRC kit deletes them, as it's harder to meter fuelling in the high RPM range with a "variable" jet.

Swapping coils/caps makes no difference?

Do you have stock exhausts to try? How old are the TYGAs? There was a very early batch, many years ago, where one side was built incorrectly. StephenRC45 struggled and struggled with his R6K until he measured up the pipe and found a flaw. TYGA replaced it, and all was well again. But as I say, that was just an early batch, and just one pipe. I can't remember which side, but if you bought them second hand, who knows? Really running out of ideas, sorry. It's so difficult when spread out over such a long time, and when the bike's not sat in front of me. With so much going on, I forget what's been tried. (Well, I am getting old!!)


Really, the RC Valves being a little out won't make that much difference. It should still pull well, and into the power band. I am still leaning more towards an ECU issue. I pinned a set of RC Valves open on a friend's R2J in Florida years ago, and it went like a scalded cat! Lots of clutch required, but I couldn't touch him riding another mate's RF900 around the little track we were on!
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