I take it alot of people mod there heads to put the plug straight.
Without looking into it im gessing its just weld up the old hole, drill & tap a new thread?
I did it with the rgv as the angled plug is pretty shite for getting the burn anywhere near right, and the gains were good!
I'll do it to the nsr too, maybe try some rs250 heads first.. could save a lot of bother! _________________ More **** two strokes than you can shake a **** stick at.
You'll have just as much bother fitting RS250 heads as you will welding & machining MC18 heads to get the plug in the middle.
The gain won't be as great as you imagine either. It's not a weak point on the MC18, although HRC did produce heads for both the Mk1 and Mk2. By the time the MC21 came out they must have realised it wasn't worth it though, as none are available for the later bikes yet they still make better power. _________________ Andy.
NSR-WORLD.COM
Please keep all responses to Forum posts on the Forum so that others may benefit.
Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.
Ok Cheers Andy, I'll do the rest of the work then think on it a bit more.
Any ideas as to my question on the ingition restrictions on the mc16 cdi'd? _________________ More **** two strokes than you can shake a **** stick at.
I beg to differ. The advantage of central plugs is better control of the flame front during combustion.
Typically (during race use) the stock front head of the 21/28 suffers detonation on the front edge. To control this we'd run richer than optimal jetting, lower comp, less advance etc etc, all the things you don't want to do. Throw on a rear head the front pot and the problem is much reduced.
But the MC16 and MC18 run lower compression than the MC21 and MC28 for a start, he's not trying to get 72~74hp out of it, and the front head on the MC16/MC18 is the same design as the rear head, so already "what HRC did" for the MC21 and MC28!
Sure, centre mounted plugs are always a good idea from an engineering point of view, but it's an awful lot of work when it's not really necessary in this case. Now if you were trying for a 75hp MC16, then I'd say go for it! _________________ Andy.
NSR-WORLD.COM
Please keep all responses to Forum posts on the Forum so that others may benefit.
Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.
I dont think it should be that hard, ally bar and cut a thread same size as the spark plug, wind in and weld, job done, drill new hole in the center and tap a new thread in.
BUT like I said I know nothing about the NSR motor as ive never worked on one.
To add to the head thread how many of you have eather O'ringed the head or O'ringed the top of the barrels? Its just ive not pulled one of these motors apart so dont know what clearences there are.
I gess 2smoke your going to get the Squish set at under 1mm or closer to 0.8mm. Should be easy enough with single heads. One big mistake though that alot of people make is skiming the head to do the squish and forgeting to recut the chamber to get the compresion back to near where it was.
Andy wrote:but it's an awful lot of work when it's not really necessary in this case.
Ere, I'll grant you that it's not really necessary, but hey, is an NSR 'really' necessary?
Owning an NSR is all about fun and experimentation and just...well...giving it a go! That's why it's so hard to find a stocker.
Even if you're running a fully stock bike then central plugs will make a difference as it can be set up to be more efficient. I say do it and then everyone can send their 16 & 18 heads to you for the mod
Oh, and seeing as central plugs ain't necessary you may as well send your central plug heads to me Andy. Just stock 'em in your pocket and bring 'em over.
I've been away for a few days so havn't been able to do anything.
I've seen MC18 heads that have been welded up hence why I started to cut heads up to look inside (pics in the members area). When it came to it though the different casting of the HRC heads makes more sense as a lot more water jacket is retained. _________________ If I have to take the carbs off once more...
Andy wrote:he's not trying to get 72~74hp out of it,
No but I'm aiming for late 60's to 70hp.
I do have experience with the 'oh so inferior' rgv engine, and between running standard heads, kit heads and re-designed centre plugged 'standard' heads. So do understand the advantages.
I'll be running 0.8mm squish, anything less I have found to be a headache, although my tz would run less but seemed a bit less eager to rev at the top.
Cheers Matt for that..
Now can anyone answer my bloody ignition query please? _________________ More **** two strokes than you can shake a **** stick at.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum You cannot attach files in this forum You cannot download files in this forum
