My GK76a winter service/tidy-up project.

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Hubbskiboy
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Bike owned: GK76A 1993 and 1990
Location: West Midlands
Re: My GK76a winter service/tidy-up project.

Post by Hubbskiboy » Thu Apr 28, 2016 7:11 pm

Wullie,
Have you had any of the mild steel parts on your bike zinc plated or any other kind of plating for that matter?
I've got an increasing pile of parts that look really corroded no matter how much I scrub them with 00 wire wool.
Had a couple of them vapour blasted, including the foot peg holders, which come up really nice when they're done.
But unfortunately as soon as any water touches them, they rust in a nano second. :down:
I've contacted a few local metal finishers/platers, but they want to charge around £70 even for a few small parts.
I suppose they can't be bothering with poxy little orders, so they just charge a stupid amount to discourage people.
Got about 12 parts now that need some treatment.
Advice please! ;)
Ta,
Hubbskiboy.

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

Post by wullie3xv9 » Sun May 15, 2016 5:15 pm

Sorry for my slow response, Hubbskiboy, I've just got my computer back from having a new hard-drive fitted! :down:
The only bright metalwork on my bike are new OEM parts which came with the bike when I bought it. Nothing was sent away for replating because I wasn't carrying out a full blown resto, just a tidy-up to make it more presentable.
If I spent a whole load of money on a full resto I wouldn't want to ride it, especially if the weather was iffy, LOL !

While I'm here I'll post a quick update. I tried a set of #55 Power Jets but they were too big, causing the engine to bog down if given the slightest bit of throttle so have gone back to the #52.5's.
But, as an experiment, I've raised the needle's half a clip position, to between slot 4 & 5, by using the old mixture screw washers as spacers, sliding them over the needle's so they're between the clip & the slide.
The throttle response has improved when the throttle is cracked open between 3 & 6-7 thou, but there's still some hesitation if it's too big a handful.
Rolling the throttle open has also improved, so I'm gonna go the whole hog & raise the needle's to their highest position & see how it responds.

Set up as it is now it's the best it's been & is perfectly rideable below 6 thou, as long as you don't give it too much throttle too quickly, as it stutters away until you close the throttle slightly & then wind it on again a bit more slowly! :roll:

Tweak by tweak tho', the throttle response IS improving below 7 thou. :grin:

Bye for now.

Wullie.

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

Post by Hubbskiboy » Fri May 20, 2016 2:35 pm

You know what's it's like.
I only started out wanting to get the bike running and looking fairly presentable, but the more you tinker with it, the more I want to get it looking mint.
I love this bike and I haven't even ridden it yet! :whistle:
Oh well, I'll probably end up just polishing it and riding it once a year like you say.
I've managed to locate a place that zinc plates on a small scale on an industrial estate near me, but it's a bit rough and ready.
Think I'll just give them stuff that doesn't damage easily to begin with.
Finally finished the carbs rebuild. I was just waiting for some replacement bowl drain bolts from Japan, which took ages to arrive! :(
https://www.dropbox.com/sh/8vbyz8rbdyi8 ... l86Ta?dl=0

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

Post by Hubbskiboy » Sun Jun 05, 2016 8:18 am

Hi Wullie,
Just been trawling the internet for the stock spec on the protrusion height of the GK76A forks.
But as per usual, I could only find a few 'suggestions'. :roll:
I need to change the seals and the oil as you have done yourself and I will obviously take a note of what height my forks are currently setup as before I start any work.
Looking at the bikes currently listed on eBay, as a rough visual guess, they seem to range from flush with the yokes up to about 10mm. I think mine are about 7mm.
What height have you got yours setup?
BTW, I dropped off my rear sprocket at the Zinc Platers yesterday as it was showing hardly any wear but looked really grotty.
I'll send you a picture of the results when I get it back on Tuesday!

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

Post by wullie3xv9 » Tue Feb 21, 2017 6:20 pm

My sincere apologies for taking so long to reply to your question, Hubbskiboy. :oops: :oops: :oops:
I've had very little time to myself over the last few months due to being very busy with work AND contending with a house move! My GK76 & 3XV were rarely touched, never mind ridden, over the latter half of last year. :cry:
I still have a few jobs to do to my GK76 that were supposed to be done last year ! :roll:

Anyhoo, to ( finally :whistle: ) answer your question, on mine I have the top of the fork tubes ( not the spring caps ) flush with the top of the holes in the top yoke.

Regarding the jobs to be done on my '76, once some better weather appears it needs :-

1. A persistant oil weep from the top of the L/H sprag cutch cover needs sorted. The weep is from one of the two cover bolt holes that I repaired with JB Weld liquid metal. (I'll replace the oil & filter at the same time ).

2. I have an 88 deg. C thermostat to fit which is made by "Blue Print". It's a (44 mm diameter) t/stat to fit Suzuki 1.3 Samurai cars! (sourced on ebay for approx. £12.00 ;) ). The "Blue Print" Part No. is :- ADK89203.
I've compared it to the old OEM 76.5 deg C GK76 thermostat & they look identical.
(There's an 82 deg. C t/stat from an SV 650. currently fitted, but the temp. needle still barely gets into the normal zone! ).
The coolant will be replaced at the same time.

3. I've also got a new o-ring seal to fit to the starter motor to cure a very slight oil weep there.

4. I've got a spare sidestand assembly, complete with new pivot bolt, that my mate Mike bushed to remove the excess free play. It just needs bead blasting & painted before fitting. (The stand assembly currently fitted has so much excess free play that when it's raised it droops down a bit ... even though a new pair of springs were fitted! :roll: )

5. The gear change lever also needs bushed to remove excess free play. (The lever could also do with a new rubber).

6. Front & rear sets of Pro Bolt stainless disc bolts to be fitted.

7. It still needs to be dyno'd to get the carburation sorted out once & for all !
(That was the No.1 job last year ... but it never happened. :roll: ).

I'm also seriousley considering replacing the stock fork springs with some stiffer ones. I see Hagon, amongst others, makes them for the non SP GK76's. As is, even with the spring pre-load adjusters wound in virtually all the way, it's still too soft for my 84 Kg carcase, plus, 1/3 of the suspension travel is used up by the weight of the bike alone AND it bottoms out regularly when going over bumps when hard on the front brakes! Not good for confidence. :whistle:
Spring's not far away so hopefully there's some good weather days AND I get some spare time to get the work above done.

Ch'o the noo.

Wullie. :grin:
Last edited by wullie3xv9 on Tue Mar 07, 2017 4:58 pm, edited 1 time in total.

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

Post by Hubbskiboy » Tue Mar 07, 2017 11:44 am

Hi Wullie,

Good to hear from you again! :grin:
I was getting worried about you, as bikers tend to disappear of the radar quite frequently. :(
Thanks for the info. You have confirmed what I suspected.
My top tubes of the forks are now sitting flush with the yoke.
Just for your amusement, here's a link to a selection of photos from my own rebuild.
I've pretty much done a complete nut and bolt rebuild apart from the gearbox and clutch.
Haven't photographed everything religiously, but hopefully you can see the standards I'm aiming for. ;)
https://app.box.com/s/1o316f2ejbxbuwioo6n6wsna66qvse9c

Keep in touch!
Hubbskiboy.

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

Post by wullie3xv9 » Tue Mar 07, 2017 6:07 pm

Thanks H, I had a look at your photos' on your rebuild thread, it'll be a cracker when it's finished. 8-)
It'll be rarely used tho' seeing as it rains so much down your way! :whistle: :grin:

I've gotten back to playing with the carburation on mine again after Stripes1976 kindly gave me a few pointers last weekend. 8-) Last Tuesday I lowered the needle's from slot 4.5 to 3.5. ( I've used the old mixture screw washers to lift the needles half a slot ! :whistle: ). A test ride confirmed the throttle response between 2 & 6 thou had improved slightly. It also felt crisper/pulled harder between 6 & 8 thou. which was where I thought the Sandy bike spares down pipes were causing a flat spot.

Today I replaced the 120 mains I had fitted with a set of 112.5's & during the subsequent test ride I had to adjust the mixture screws from 1 & a half turns out to 2 & a quarter turns out as the engine cut out a couple of times at junctions/round-abouts & was a pig to get started ! :roll: ( Lean cut ?? ).

Again, there's been another slight improvement with the throttle response. I can roll it open even more aggresively between 3 & 6 thou., tho' it still "machine gun" stutters slightly, but stops when I roll off the throttle slightly.
From 6 to 12 thou., in 6th gear, it pulls progressivley harder. It's a nice, linear delivery. ;)

Even with 15/44 final gearing, it romped past the 180 K mark, & when cruising at 6-8 thou. the temp. gauge needle spends more time just above the C (for Centigrade) on the gauge face.
(It currently has an SV 650 82 deg. C thermostat fitted & have an 88 deg. C t/stat to fit ).

Next chance I get I'll remove the old mixture screw spacers from the needles to set them slightly lower at the (stock) middle slot to see if that reduces/gets rid of the "machine gun" stuttering between 3 & 6 thou.
Once I've cracked that particular problem it might finally get run on the local Dynajet rig to check the fueling out properly!
It has improved though so it's nearly there, carburation wise. :smile:

Till next time, folks.

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

Post by Hubbskiboy » Sat Mar 25, 2017 8:00 pm

Hi Wullie,

Another question for you.
When I finally get round to putting the fuel tank back on the bike, I was hoping you could give me some advice re: the fuel plumbing!
Both the manuals I have in my possession are pretty poor for detailing the fueling system from the tank to the carbs.
To help you, (help me) I've attached one of your previous photos and numbered the petrol tank outlets 1-4.
Rather stupidly I didn't pay any attention when I was dismantling this part of the bike (right at the start of the adventure!)
I was hoping that you could tell me what hose I need to attach to each port?
A photo would be even better if you have one?
All the ones in the Jap manual are black and white and I can't see jack sh*t.
Cheers mate!

Image

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

Post by moforockband » Sat Mar 25, 2017 10:25 pm

I can help.

1. water/overflow drain hose to atmosphere (hose to bottom of bike)
2. Vacuum connection to carb top or inlet rubber (not sure exactly which on 76a)
3+4 fuel flow to carburettors

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

Post by Hubbskiboy » Sun Mar 26, 2017 6:02 pm

Thanks Mofo.
So I'm guessing that it doesn't matter if you get 3 & 4 mixed up as long as they both go to the left and right fuel inlets for the carbs, correct?

Onto the next question. Hopefully either yourself of Wullie can help me with this one.
I've been fiddling around with the brake system on my bike for the last couple of days. :( :? :x
It's a total rebuild including the callipers and master cylinders and new hoses so obviously it was a completely dry system.
No matter how much fiddling and tinkering I do, I just can't get any pressure in either the front or rear brake lines.
Am I missing some secret method of doing this?
I've tried sucking all the air out through the bleed nipples using a humungous syringe I pinched from work and then the usual open/close bleed bolts whilst pressing the brake levers.
Now I'm definitely only getting brake fluid from the bleed nipples - no air at all.
I've also tapped all over with a small rubber mallet to dislodge any air bubbles.
The brake pads move only very slightly when I press the brake lever.
But they just won't build any pressure and certainly not enough to stop the wheel spinning on a paddock stand!
I could understand one of the brake systems being a bugger to setup, but because it's both the front and back I guess that I'm making a huge cockup of this process.
Is there a special tool that I can buy to make it an easier process?

Cheers,
Hubbskiboy.


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