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Nsr250 Mc21se Rothnans


paul8899
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I thought I'd start a thread about a sickly nsr I just bought to replace my 3ma

This is how it looked when it arrived

20160902_110311_zpsyerzci9x.jpg

20160902_110339_zpss7igpyel.jpg

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After spending an hour working out how the bodwork comes off it ended up looking like this

20160902_125951_zps7n9mhfhx.jpg

Hopefully it won't stay like this for long ( famous last words )

The bike has got some replica panels fitted and I'm quite impressed with them, the thickness of them is about the same as oe and the fit is pretty good as well.

One of the things that I noticed with the fairings off is that the engine is tiny compared to the 3ma, there's still a load of wires and gubbins hidden away which is the same as a 3ma so I don't feel completely lost :)

The bike runs really rough which could be an ignition or fuelling problem, so I chose to take the carbs off first because I had to turn the bike around to get to the flywheel and it was raining. When I took the carbs apart they were clean so I gave them a quick spray with carb cleaner, a quick check and then re-fitted them, the bike still ran rough. So off with the carbs again. When I was messing around with the 3ma the float level made a difference to how it fuelled so when I took the carbs apart this time I reset the float height and tried again, still no joy :( Although it did make a nice change not to have to lay on the floor to take the carbs off  

The next thing I tried was to remove the airbox to see if it was running rich which didn't make any difference.

I then checked the pipework and unions on the airjet system to see if they were blocked but they were clear, so it wasn't those either.

I checked the plugs and they were wet so the fuel is getting in so that leaves the ignition. I don't think the pgm box is broken as the powervalve servo motor moves when the engine runs so that leaves the flywheel. When I bought the bike the seller wasn't sure if it had a mc28 flywheel fitted so I'll change that for a mc21 one tomorrow to see if that cures it.

Compared to the 3ma the nsr has a slightly better build quality but it seems to have the same amount of wiring and tubes hidden away.

Once I've got it running nicely the plan is to strip it down and get the wheels, subframe and clock bracket powder coated and give it a thorough clean.

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Those are the next on the list to check.

I've got the service manual but I'll probably need help checking them ( I'm not very good with electics :) )

I checked the flywheel ( both the one on the bike and the spare ) and they are both the same and from a mc28. I'll get a proper 21 flywheel to try and hopefully that will fix it.

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Being as it seems like the bike is going to spend a lot of time up on stands I thought I'd make some lifters.

20160905_181510_zpsvuatyxoh.jpg

When I was measuring up the lifters I saw that I might be able to make a couple of bits for the swingarm but that will ( might ) have to wait until it's running.

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Just had a quick check on where the flywheel lobes are in relation to tdc and if the pick ups line up with the lobes

On the flywheel there's 2 pairs of lobes that are close to each other, hope this makes sense !

When the top cylinder is at tdc the 2nd lobe of the pair is under the top pick up

When the bottom cylinder is at tdc the 2nd lobe of the other pair is under the top pick up

When either piston is at tdc the lobes aren't anywhere near the lower pick up, at a rough guess I would say that when the lobes are under the lower pick up it's about half way through the stroke.

Does each coil have its own pick up ?

 

 

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Right, just checked through the manual and how the flywheel is on mine matches the picture in the manual

ignition%201_zpsldbhweno.jpg

As it's shown the top cylinder is at tdc but when the bottom cylinder is at tdc the lower lobe is is under the top pick up but there's nothing under the lower pick up.

According to the manual each pick up triggers a coil but I can't see how it would do that as there isn't a pick up near a lobe when the bottom cylinder is at tdc

Stupid motorbikes !

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After having a think about what the engine was doing when I could get it to start I had a few choices as to why it was running badly.

The choices were,

Buggered pistons / engine

Electrical fault

Being that I didn't really want to start spending any more money on this I went with the cheaper option of checking the loom.

As the flywheel lobes were lining up with the pick ups when they were supposed to I thought it would be best to start from the flywheel and work my way up the loom from there.

So off with the pick ups it was, the pick up trigger had a load of muck on them so I cleaned them off so they were nice and shiny. I then decided to unplug them to give that part of the loom a wipe down which is when I found a big lump of insulation tape.

I stripped the tape off and found this

IMG-20160907-WA0000_zps88zu8k1i.jpeg

You'll notice the lack of solder and that the wires are just twisted together. After 10 minutes they looked like this

20160907_180515_zpsbjsymhl4.jpg

I didn't take a picture of how it looked once it was finished because I wanted to try it out straight away.

After a couple of kicks this happened :)

It is still running a bit lumpy but I'm putting that down to the bike being full of crap from being run with it misfiring,

Now that it runs reasonable the plan is

Change the plugs,oil and filter

Take the exhausts off to see what comes out

Clean the power valves out, when the bike is restricted the power valves only open about half way and they might not open up properly which apparently makes the pgm box blow up and at £3-400 a go that's something I really don't want to happen.

Set all the cables etc up properly

Give it a good check over to make sure everything is ok and nothing is going to fall off

Give it a damn good thrashing :)

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The lobe that triggers the ignition must go past the pick up BEFORE TDC , I never worked out why Honda put 4 lobes on the flywheel when you only need 1. For a good laugh go the NSR world and type in "PGM fail", lucky you can buy a Zeeltronic or Ignitech now and throw the dodgy PGM away

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5 hours ago, 2T Institue said:

The lobe that triggers the ignition must go past the pick up BEFORE TDC , I never worked out why Honda put 4 lobes on the flywheel when you only need 1. For a good laugh go the NSR world and type in "PGM fail", lucky you can buy a Zeeltronic or Ignitech now and throw the dodgy PGM away

The lobes were only roughly checked ( allen key down the plug hole ) so they might be a bit out. I've got a dti adapter that I'll check it with over the weekend

I've tried a spare pgm box but had the same results, the spark is nice and strong since I've soldered the wires together but it still won't start

The reason I'll be checking it again is because I tried to start the bike again today but didn't have any joy.

I'll get some damp start and give that a try or I might take the heads off and have a look a bit deeper

This is starting to make my old 3ma seem like a doddle !

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Being as I've got the sulks because the bike isn't starting I thought I'd start making it look a but nicer by getting the wheels, subframe and various brackets powder coated.

After about an hour the bike looked like this

IMG-20160910-WA0000_zps7yrfapzn.jpeg

I noticed that the swingarm looked a bit manky which led to the bike looking like this

IMG_20160910_171747_zpsmbmrsmec.jpg

One manky swingarm

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After an hour with the scotchbrite and wd40 it now looks a bit nicer

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IMG_20160910_181418_zpsze72loo8.jpg

Just have to clean the rest of it now !

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Now that I've fitted the swingarm back in I thought I'd better check where the flywheel lobes are in relation to the pick ups at tdc.

This is how they looked at tdc

20160911_182326_zpsawddxhxy.jpg

I measured it when the front edge of the flywheel lobe was just touching the pick up and it was half a mm away from tdc.

I'm going to remove the woodruff key and try and set the lobe so it's 2mm away from the pick up tdc and see if that works.

This is how far the pick up is when it's 2mm away from tdc

IMG-20160911-WA0011_zpsslli9zm2.jpeg

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I had a play around with the timing yesterday but still ended up with a non running bike. After kicking it over for 30 minutes I copped the hump and left it

One thing I did that worked was the flywheel holding tool that I made

20160912_182909_zpsnfyhhrsr.jpg

I then had a thought about how to turn it over quick enough ( with the minimum of work ) so here's an almost patented motogp style starter system for my nsr

I checked how it was sparking while it was being turned over and it looks like the coil for the bottom cylinder is breaking down.

I'm getting a nice fat spark from the top cylinder when I pull the plug away from the head but the bottom one only sparks when it's touching.

The next thing I'll try is swapping the coils over to see if the bottom cylinder will fire up.

Hopefully the problem will change cylinders.

If the problem does change cylinders I'll put the timing back to where it was and see what happens

Does anyone know if I can use other make coils or do they have to be oe ones ?

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i had a coil issue on my nsr, it was starting fine but breaking down at high revs. 

If i remember i ordered some new honda ones from tyga or it might of even been honda UK, i think they were used on some UK bikes. 

Its going back a few years but just check the spade terminals on the coils and the connecting wires as they can corrode a bit or the wires get flakey. 

I had a honda RS125 at the time and think i diagnosed it by using the coil of that. 

 

Assuming the right flywheel is fitted and no one messed around with the woodruff key i'd leave it all alone. The pick up coils do fail but its pretty rare. 

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Hi Paul good to see another nsr project on here, I will have a spare pair of nsr coils somewhere you can borrow if you like.

Is that just a socket in your drill you are using to start it or one of those special starter thingys you use in a drill? 

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17 hours ago, Dexter21 said:

These have a reputation of working well with NSRs

http://www.webike.net/sd/1331418/

Thanks for the link , I'll have a look into those

 

9 hours ago, ricey3 said:

i had a coil issue on my nsr, it was starting fine but breaking down at high revs. 

If i remember i ordered some new honda ones from tyga or it might of even been honda UK, i think they were used on some UK bikes. 

Its going back a few years but just check the spade terminals on the coils and the connecting wires as they can corrode a bit or the wires get flakey. 

I had a honda RS125 at the time and think i diagnosed it by using the coil of that. 

 

Assuming the right flywheel is fitted and no one messed around with the woodruff key i'd leave it all alone. The pick up coils do fail but its pretty rare. 

I'll have to see which models have the same part number as the ones on the nsr and see how expensive they are compared to aftermarket ones.

When I swap the coils over I'll check the wiring as well and see how it looks

Once I've got it sparking on both cylinders I'll reset the flywheel and then just fill it up with petrol and oil :)

 

4 hours ago, paul g said:

Hi Paul good to see another nsr project on here, I will have a spare pair of nsr coils somewhere you can borrow if you like.

Is that just a socket in your drill you are using to start it or one of those special starter thingys you use in a drill? 

Hi Paul, good to see another Paul on here, you can never have enough Paul's !

Thanks for the offer of borrowing the coils, if I don;t have any joy I'll be in touch

It's just a socket attached to a drill :)

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Coil or a dodgy spark plug/plug lead/cap or cap/lead connection not good.

Dead PGM's are dead, not just working badly and nearly always from badly (not) serviced power valves.

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1 minute ago, fontyyy said:

Coil or a dodgy spark plug/plug lead/cap or cap/lead connection not good.

Dead PGM's are dead, not just working badly and nearly always from badly (not) serviced power valves.

I swapped the plugs over to see if it was a dodgy plug but the problem was still on the bottom cylinder, I'll swap the coils over and hopefully it will change cylinders or I'll be having to check the wiring and connectors

Good to know that a dead pgm just doesn't work instead of working badly :thumbsup:  Servicing the power valves is next on the list once it's running properly

I don't suppose you know if this flywheel ( 037000-2641 ) is from a mc21 ?

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5 minutes ago, paul8899 said:

I swapped the plugs over to see if it was a dodgy plug but the problem was still on the bottom cylinder, I'll swap the coils over and hopefully it will change cylinders or I'll be having to check the wiring and connectors

Good to know that a dead pgm just doesn't work instead of working badly :thumbsup:  Servicing the power valves is next on the list once it's running properly

I don't suppose you know if this flywheel ( 037000-2641 ) is from a mc21 ?

http://nsr250.net/forums/viewtopic.php?t=6578&highlight=flywheel

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2 hours ago, paul8899 said:

 

Hi Paul, good to see another Paul on here, you can never have enough Paul's !

Thanks for the offer of borrowing the coils, if I don;t have any joy I'll be in touch

It's just a socket attached to a drill :)

Give us a shout if you need the coils. Im building an nsr with a f3 engine so no kickstart, tried to start it using the same method but my drill wasnt powerful enough to turn :unsure:

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5 minutes ago, paul g said:

Give us a shout if you need the coils. Im building an nsr with a f3 engine so no kickstart, tried to start it using the same method but my drill wasnt powerful enough to turn :unsure:

That means that either you have a great motor or a shit drill. what is the case?

 

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3 hours ago, paul8899 said:

I don't suppose you know if this flywheel ( 037000-2641 ) is from a mc21 ?

No idea, but it won't cause bad running, just a slight loss of power due to being a tad retarded.

Edited by fontyyy
speeling
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31 minutes ago, fontyyy said:

No idea, but it won't cause bad running, just a slight loss of power due to bring a tad retarded.

:blink:

That's a bit harsh, he only asked a question FFS!

 

Oh, you mean... :eusa_whistle:

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