My GK76a winter service/tidy-up project.

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wullie3xv9
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Bike owned: GK76a GSXR400R & TZR250RS
Location: Fife, Scotland
Re: My GK76a winter service/tidy-up project.

Post by wullie3xv9 » Wed Feb 24, 2016 12:43 pm

Hubbskiboy, I'm lucky in that I have access to waste AvGas at work so used that along wi' brushes & elbow grease.
Gunk or Jizer would have been the obvious candidates if it wasn't for the AvGas. Well done on finding a bent choke valve, replacing that should help free up the system. :grin: As VVS says, removing the engine is do-able yourself.
Like VVS I also used a trolley jack & sturdy piece of flat wood to help support the weight of the engine during engine bolt removal. Watch your back when you come to lift it yourself as it's a heavy lump!

As yet I haven't needed any 4 stroke engine specialists, but, I've stripped/overhauled a car cylinder head in the past so a top-end removal/rebuild holds no fears for me ... & I'm a long time 2 stroke enthusiast that rebuilds my own motors.
If you decided to try your hand on the top-end I'm sure the more experienced guys would guide you through.
Oh! Don't forget the workshop manuals are on here which come in VERY handy. ;)

Good luck with it & keep us all informed of the progress. ;)

Hubbskiboy
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Bike owned: GK76A 1994 and 1990
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Re: My GK76a winter service/tidy-up project.

Post by Hubbskiboy » Sat Mar 05, 2016 10:07 pm

Wullie. Thanks for the information. This is all good stuff.
You'll be pleased to hear that the bike build is coming along nicely.
I've bought a mini scissor lift stand to take the weight of the engine, which should be arriving any day now.
I've also printed off the entire service manual for a GSF400 (while I was at work! :whistle: ) , which as I understand it is basically the same engine as in our bikes?
I've gone through most of the manual and it looks pretty much the same to me.
Another query for you that has come about after tinkering in the garage today.
I noticed that there is an 'extra' connector when looking at the wiring loom, specifically for the radiator fans.
I thought I was loosing the plot, so I checked some of the photos I took before taking the bike to pieces, and there it was, just hanging loose.
I can send you the original photo I took if you need it, but this is what the loom looks like now -
Pretty sure the one I have circled is the one that was originally not connected to anything.
Any ideas?
Cheers.
http://i1353.photobucket.com/albums/q67 ... skfurh.jpg

Hubbskiboy
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Bike owned: GK76A 1994 and 1990
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Re: My GK76a winter service/tidy-up project.

Post by Hubbskiboy » Sat Mar 05, 2016 10:17 pm

Hi Wullie.
As mentioned previously, I though the original photo would help with my description.
As you can see, there is one of the connectors from the cooling fan wiring, just hanging loose.
Don't know why I didn't notice it before.
http://i1353.photobucket.com/albums/q67 ... eyuwiu.jpg

wullie3xv9
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Bike owned: GK76a GSXR400R & TZR250RS
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Re: My GK76a winter service/tidy-up project.

Post by wullie3xv9 » Tue Mar 15, 2016 9:29 pm

Hubbskiboy, I dragged my GK76 out today (to refit its bank of carb's) & had a look for your spare connector possability.
Looking at your two photo's it looks like you don't have an earth wire coming from the rear of the alloy part of the thermostat housing. On mine there's a ring terminal & black/white wire under the head of the L/H bolt that connects to a short black/white wire's female bullet connector that comes from the main loom, like in your photo's. Hopefully mystery solved.

Right then, time for an update. As mentioned above I've been working on my bikes carb's again. About a month ago I removed them so I could fit the new OEM needle's, O-5 needle jet's & pattern float valve needle's I'd bought & have also replaced the four 117.5 main jets with 120's. I'm hoping the new needle's & their jets cure a rough running (over rich) patch around 3,000 rpm. I also tweaked the mixture screws from one & 1/4 turns out to two turns out & balanced/set the butterflies using a length of 0.6 mm locking wire as a feeler gauge.

Image
Image

I finally got round to refitting the carb's today. (Fought with them more like, as GK76's are a bar-steward to work on! Or is it just me. :whistle: ). Thankfully the auld git fired up, (for the first time this year), settling down to a smooth, steady 1,100 rpm idle once warmed up. So far, so good. :grin: I ended the day by refitting the tail panels, seat pads, fairing middle's & lowers so she's now back in one piece again. She just needs an MOT & she's road legal for another year. Hopefully I do more than the 600 odd miles I did on it last year! :oops: (Working away from home & crap weather were the main culprits :x ).

Anyhoo. Ch'o the noo.

Wullie. :smile:
Last edited by wullie3xv9 on Tue Apr 24, 2018 4:17 pm, edited 1 time in total.

wullie3xv9
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Re: My GK76a winter service/tidy-up project.

Post by wullie3xv9 » Mon Mar 21, 2016 6:45 pm

Another quick update, folks. My wee Gixxer 400 sailed through another MOT today. :grin:
Mind you, it's only done about 570 miles since last years MOT! :oops:
After fitting the new needles & needle jets to the carb's, plus another couple of internal tweeks, it's now running better than ever. :grin: The rough running/rich patch around 3 thou. has gone, so there must have been enough wear on the old needles & needle jets for it to run rich there. It just needs the 52.5 mid-range "power jets" refitted, (up from the stock 47.5's), & it should be nigh on perfect. (As is, it now stutters/stumbles if you crack the throttle open between 4 & 7 thou., which it didn't do before! :roll: ). Above 7 thou. it,s YEEHAAAA all the way too the redline. :grin:
Once the 52.5's are fitted I can book it onto the local Dynajet rig for them to check out the air/fuel ratio through the full rev range. Here she is after todays MOT with Falkland Hill (East Lomond hill) in the back-ground.

Image

(The eagle eyed amongst you might have noticed I've replaced the front mini indicators with a pair of OEM's. ;) ).
Last edited by wullie3xv9 on Fri Apr 15, 2016 7:06 pm, edited 1 time in total.

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4hundread
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Re: My GK76a winter service/tidy-up project.

Post by 4hundread » Mon Mar 21, 2016 10:19 pm

Cracking Wullie, good work. I am hoping to be MOTd in the next couple of weeks, we will need to organise a wee meet

wullie3xv9
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Re: My GK76a winter service/tidy-up project.

Post by wullie3xv9 » Tue Mar 22, 2016 8:43 am

Thanks, Si. Aye, I'm up for a meet & a bimble. ;) Do you still want your old wavey rear disc??

wullie3xv9
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Re: My GK76a winter service/tidy-up project.

Post by wullie3xv9 » Sun Apr 10, 2016 12:38 pm

Hi folks. I finally got round to fitting the bigger set of 52.5 "Power Jets" (as they're called in the MIKUNI carb's parts book) yesterday afternoon, but haven't taken the bike out for a run yet as I'm not feeling too good at the mo'. (Sore throat, aching limbs, a bit of a temperature & a bad cough!). :( Anyhow, I had a go at replacing them with the carb's fitted to the bike & managed fine, (I removed the belly & mid fairing panel's), the L/H pair being harder than the R/H pair to work on due to the clutch cable & the metal coolant pipe & it's bleed bolt. I used one of those plastic carry-out meal tubs to drain each carb's fuel into before removing each float bowl.

Image

I mentioned in an earlier post I've treated the bike to a new pair of OEM front indicators. When I ordered the indicators & attaching parts from my local Suzuki dealer the only thing "no longer available" was the most critical part, the inner mounting plate that clamps each indicator against the mid fairing panel ! :down:
I had to resort to shaping a pattern out of plastic card, finding a scrap piece of thin but strong aluminium lying around at work & making my own mounting plates! It least all they cost me was time. ;)

Image
Image

I'll post how the bike runs with its fully revised carb settings once I'm fit enough to take it out for a test run.

Bye for now.
Last edited by wullie3xv9 on Fri Apr 15, 2016 7:07 pm, edited 1 time in total.

Hubbskiboy
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Re: My GK76a winter service/tidy-up project.

Post by Hubbskiboy » Sun Apr 10, 2016 1:17 pm

Hi Wullie.
Those OEM indicators look super cool! 8-)
I can't stand any of the aftermarket indicators as I think they look absolutely naff.
Well done on making the inner mounting plates yourself.
Looks very professional to me.
I can't believe how much room you've managed to create to work on your carbs while they're still fitted.
You should work for an Estate Agents! Your camera work makes it look like you've got armfulls of room.
I'd never work on the carbs unless they were on a work bench as it's too fiddly.
Keep an eye out for a GK76A Swingarm in mint condition for me will you?
They're as rare as a tasty school lunch. ;)
Mines got a serious amount of wear from the exhaust rubbing to the point where there can't be much aluminium left underneath! :pray:

wullie3xv9
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Bike owned: GK76a GSXR400R & TZR250RS
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Re: My GK76a winter service/tidy-up project.

Post by wullie3xv9 » Fri Apr 15, 2016 6:43 pm

Lol, I'm not a fan of mini indicators either. The Japanese spec. OEM one's are small enough for me. ;)
The R/H pair of carb's are a dawdle to work on in situ if just replacing pilot, "Power" or main jets.
The L/H pair of carb's are more awkward to work on in situ, but certainly do-able.

Right then. I used the bike for the commute to work yesterday, (a 65 mile round trip), & it needs more fine tuning!
It still needs to be richer between 4 & 7 thou. rpm as it's still stuttering/hesitating when I crack the throttle open, but pulls better than before when the throttle is rolled open, so I need to order & fit some #55 Power Jets! (Up from the #52.5's currently fitted). I also tried the mixture screws at 2.5 turns out, but have had to lean them back to 2.0 turns out as the rev's were dipping below idle rpm when the throttle was blipped from idle with the engine up to temp.

So, it's still not quite there! :roll: More updates to follow. ;)


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