Gsxr f 900 ignition advancer mod?

[Jpich85]

I'm looking to do the ignition advancer mod on my gsxr f 900 but having the 750 head on the 900 engine I wasn't sure what degrees would be best? I read that if you have an engine with more compression then you shouldn't have as much advance? I see they sell them on Eblag so was thinking about fitting one just wanted to ask if anyone knew what degrees would be best.

Cheers

 

[Madb]

750 w/c are set at 13 deg below 1500 rpm where's as rf900 is 7 degrees  below 1500 rpm, i was thinking of just using the 750 ecu and see how it works out. how much they charging for the advancer? can you not just elong the holes on the timing plate?

[Jpich85]

I think I made life hard for myself with this engine swap because it's been a pain setting up, they're charging 50 quid, all of there's are 4 degrees, do you think 4 will be ok, I have seen that mod where you elongate the holes but I'm not confident of what a actually need to do.

Do you know what the idle rev count should be mines on about 1k didn't know if that's normal for my bike?

 

[Madb]

I've not done the advance as yet now in the process of building up the engine but i would leave it as is for the moment if it's running fine. more advance should make the bike feel a bit more reponsive but . 1k is round the park tho may sound lumpy tho mine as a 750 idles about that . any higher and mine sounds like its on choke! but could just be me!  do you know the exact copression?

[Jpich85]

Unfortunately I haven't checked the compression yet, I know it's something I should of done at the start but it's my first build and have realised a lot and the steps the bike should be made in, the bike does run nice but the carbs need a good tune, I put some 147.5 main jets in and that was about it for the carbs, it's got a short exhaust and pod filters too, I was just expecting more pull from the bike?

[Jpich85]

Sorry one more question if you running pod filters, what do you do with the rocker cover breather? I did put a small filter on there but wasn't sure if that could be restricting it somehow?

[Madb]

Sorry for the delay, been busy doing my engine. Just fitted 750 head on my engine , unfortunalty the shims are to tight so thats tomorows job ,hopefully engine in frame saturday aftenoon if i have the shims.

carbs do need to be checked on rolling road if you have'nt yet. you'll gain by doing so. fueling may be running a bit rich, how are the plugs and the end can outlet? is it very black and sooty?  the pull should be arm wretching! how far have you rev the old gal? 

[Jpich85]

Hi madb, Are you doing the rf900 engine swap too? I hope you're progressing well with the engine mate,

I would like to get it dynoed but the local place here the bloke is a bit of a nob so I've never took it there once, the end can isn't that bad and the plugs aren't too bad, I have 147.5 main jets, what have you gone for?

I'm not sure if I'm brave enough I've only gone to about 8k in the revs, when does the limiter hit in? It is really torquey tho, I wondered if the rf900 gear box might be geared more for low down power. Cheers

 

 

 

[Madb]

Yes, now fitted head to 900 bottom end. pick up an engine this week rather cheap, so fitted 750 head to that engine, the one i started to build is on bench but being very anul about that one as it will be my mule for testing upgrades on.  just need some 1.5mm shims and engine will be fitted to road bike. As for the main jets, i were going to start at 130 and go from there. i,m using ram air socks so be interesting. do you find yours a bit fluffy at low revs or does it pick up ok? as for the rev limet should be about 11000 to 12000. as for the gear box being low geared. i would have thought it's about the same as the 750 just longer gears as it's only five speed. I,ve not ridden an rf900 but by the 1/4mile figures i would say it,s quite a bit faster than my 750 and that aint slow, standard gearing are 15 front 43 rear so if you would like a bit more get up then drop the front one tooth. mind tho as it will be a wheelie monster with a hand full of thottle.  what colour are the plugs?

oh and as for the breather pipe i would find a small bottle to put the end in and have the filter come off a seperate pipe from that i.e. like two straws coming out of a bottle one for the breather and other for the filter.

[Jpich85]

Thanks for getting back to me, mine seems ok on pick up the throttle seems a little jumpy when I first twist it tho, what do you think that could be?

My gears are 15 and 45 I thought that was standard but my research may have been wrong, do you think that's the wrong gearing set up? I'll check the plugs over this week and let you know, I haven't time to check them recently, I've been working on the exhaust a little.

What headers are you using?

 

 

 

[bluedog59]

From what I've found developing a pipe when I was racing and talking to dyno operators, Short pipe don't work.

I know people will say they've got a short pipe and it's great but, how great ? Have they run it back to back against a full length system on a dyno ?  

[Madb]

@bluedog says, short pipes dont work.  the lengh needs to be long for the exhaust timing to work proper ,i.e. back  pressure  and other stuff all come into play with the torque curve and where it works along the rev range. that lengh also includes the link pipe to. to short and the bike will feel a bit gutless higher up the revs. not that you need to change anything just yet. if yer bike is running fine just get lots of miles under yer belt and enjoy the ride.  tinkering can come later.

pipes i shall be using are either  k1 thou or some old yoshis i have (which need work) still need a link pipe tho.

your gearing is prefect for the time being.  rear probably is 45 so a couple of teeth lower than 750 wn but then it all depends on the ratio in the gearbox how close they are to 750. i will have a look as i would rather have the get up and go then stop speed .

[bluedog59]

I'm not saying you can't have a short pipe, have what you want but accept that, ultimately, they are not good. If you get it running good enough to use and it's not hurting it, use it.

[Jpich85]

Thanks guys I kind of mate the exhaust us as I went she with what parts I had, I had the original headers but they didn't fit because the rf900 engine is slightly taller so I chopped the pipes and welded sleeves between the two bits to extend it, I bit dodgy I know but it's what i did at the time, then i stuck the short can on the end of the headers because the link pipe didnt work, I'd love a nice stainless system tho but didn't know what headers would fit without too much hacking,

so you think k1 headers work? If so I'll buy some :-).

I  took the bike out tonight and was feeling brave, I haven't really took it past 8k yet on the revs but I pushed it a bit more up the bypass and man it felt good there is so much more to the bike that I haven't felt yet but I won't be doing that too often, like you said I need to get use to it yet and enjoy it :-).

so if I dropped to 43 on the back the acceleration would be greater?

Thanks again for your help

 

 

 

 

 

 

 

 

[Madb]

smaller sprocket on the front or bigger on the back sprocket will give you more accelleration. normally one tooth off the front as it does'nt alter the chain lengh as much and cheaper than a bigger rear. One tooth off the front equals three off the rear.

haha, yes, it is a buzz,and rush but do be carefull. track day would be the better place with instructor to help with the control. these days you need eyes in every orifice of yer body as most car drivers dont give a f@@k about anyone else on the road. i driven lorrys for thirty years and i still have car drivers saying "sorry, i dint see you!!!? lorry i used to drive was 12ft high 8ft wide 60ft long for christ sake!!! What part dint they see??? so do be carefull where and when.

k1 pipes will work ok for you. some dont like the way they sit on the bike but they're light and cheap. 

Edited June 26, 2017 by Madb
info

[Captain Chaos]

no matter how visible you are, people who don't look can not see you

[Jpich85]

 

Don't worry I'm kind of a steady eddie atm as I'm still learning, I get people overtake me quite often which is a little embarrassing lol, it is a rush but I understand how dangerous it can be too, I don't to wreck my pride and enjoy either lol. That's crazy some people must be half asleep, I think the oaps are really bad too,

thanks for your tips madb, could you let me know how you get on with your carb tune as I'm not to experienced with that side of the bike and could do with some pointers.

Did you change any of the electronics or keep it all gsxr 750?

 

 

 

Edited June 27, 2017 by Jpich85

[Madb]

@Captain Chaos,  i've had them looking straight at me and still pull out!. some people just should not be behind a wheel!. just have to watch them pushing shopping trollies! thats scary enough. haha. mate has just left the worskop and guess what! he has just encountered a driver coming towards him the wrong way up the one way system!!!

Anyways, glad to hear you're a steady eddy. don,t worry about people over taking you.  you ride at your own speed. don't let anyone hassle ya. life is too short to worry.

As for the carbs as shall let ya know how it goes. just order shum 140 mains so we'll shall keep notes so you can learn from it all. I'll keep an update in my project.

electronics shall be 750 as i don't have the rf9 ecu. which ecu are you using?

[badgerkdd]

This is real useful for me too, I'm planning on doing the Rf900/ 750 head mod myself when time and funds allow, so i'm taking notes....

[Jpich85]

Lol that's true madb, I had someone pull out on me as if I wasn't even there then she gave me the look of death as if it was my fault lol,

i checked the plugs tonight, I'm no expert but my dad said they look pretty good, not white and not to black so it isn't too bad. I'm using 750 electronics too I thought I had the 900 one around in a box of bits I got but I haven't tried it as it seems ok, what would the rf900 ecu do? 

I've been working on a custom expansion tank and rad cover, I'll post a pic when I can.

 

 

 

 

[Jpich85]

[Jpich85]

[Madb]

fueling seems spot on then, thats cool. gives me a good starting point.( must write this down.) 

Your bike looks brutal! in that stance. loving the look. You should pat youre self on the back! ya done proud!.

Just arrived. Shims!! and Jets!! jay.. can get on a bit more now. still need my sprocket cover tho! grrrr.

[Madb]

Oh and love your expansion bottle. nice touch!

[badgerkdd]

Like the look too, mean ...