Hi All!

Being new to the forum, my name is Greg and i've found myself with a GSXR 400 in my garage

I did my research before buying the bike and came across this great forum. I saw that the o-rings can cause problems so kept that in mind when viewing the bike. Everything seemed OK, if not running a little rich.

After having the bike for 2 weeks now, I decided to order a Morgan Carbtune and O-rings from PolyMax - I am awaiting both deliveries.

In the mean time, I thought I would ask a couple questions based on my bike;

-I don't need any choke to start the bike (in cold Scotland)
-The temperature gauge doesn't work/Don't believe the fan comes on
-When cold it has a slight hesitation when using the throttle
-Black exhaust tip
-Revs cleanly in 1-4th, but seems to starve for fuel at around 12,000rpm in 5th and 6th
-Idles around 1500rpm when cold, 2000-2800rpm when warm (seems to vary at certain points)
-Slight rattling kind of noise when idling - is this a cam chain tensioner problems?

I believe these are signs that the bike is running rich! So upon delivery of the orings and carbtune, I will set out to change the orings and balance the carbs correctly in hope there are no other problems with the carbs

The bike has a yoshimura exhaust on it - should I still set the mixture screws to 1.5 turns out? (I don't know what they are currently sitting at since i've not had the carbs off)

When trying to get the bike to idle correctly after the orings have been changed, should it just be a case of using the idling screw (the thumb wheel)?

Now, the rattle..
I only noticed it after riding the bike for around 10 minutes one day. From reading the forums, i understand that this era of Suzuki bikes used automatic cam chain tensioners and these can reach their maximum travel.
Would buying another one from eBay solve my problem, or should I look at buying a manual tensioner?

To replace the tensioner, is it a case of removing the existing one and installing a new one? If not, could someone please advise

As I currently have the fairings off the bike, I will introduce myself to the forum with pictures once I get the carbs and cam chain sorted

Thanks in advance,
Greg

Hi Greg,

If the rattle is cam chain tensioner then the sound will be coming from below the carbs in the middle, take a long screwdriver hold it against that part and put your ear to the driver and it will help you to hear better.
Its most likely coming from up top and will be valves needing adjustment.

Not needing choke and temp staying low are a sine that the orings are bad and the motor is rich from the extra fuel,
Have a check of the wiring around the thermostat housing as some of the wires are similar colours a d people can put them in the wrong place, ita easy to vet black swapped with black and white trace etc.

Hi VVS, thanks for the reply!

I will try the screwdriver trick soon. The sound seemed to be at its loudest nearer the manifolds/front of the bike when I last checked, but I'll have another look soon.
If I were to replace the cam chain tensioner, is it a simple remove and refit?

If it were valves, are these easy to adjust on the gk76a?

I'll be sure to have a look at the wiring in that area and make sure it's connected correctly! Hopefully replacing the orings will fix the issue!

If once the orings are changed, the bike runs lean, which way should I turn the mixture screws? Anti-clockwise?

Greg

Tensioner is only held in by a couple of 6mm cap heads so very quick to change.

Its a little long winded to explain so you will be better having a google BUT if you get a carb balancer you can use it to adjust the idle screws, look on their website as may tell you there.

I'll have another listen, but might change the tensioner anyway. I was looking through all the old posts and saw that you said an srad 600 APE manual tensioner would fit. Does this one look right; http://pages.ebay.com/link/?nav=item.vi ... 1581960311
I assume that would also be a direct fit?

I'll have a look and have a play about with the carbtune once it arrives

Thanks for the pointers and quick responses, I'll let you know how I get on

If someone could let me know if this will fit, http://www.ebay.com/itm/271581960311 , i'll go ahead and order it so I can install it when I have the carbs out!

Morgan Carbtune came today, just waiting on the o-rings now

Much appreciated

I got my adjusters made by a guy in the US and was told it was for the srad but it wasn't an ape make so only ever took his word that it was srad fitment.
Ive spoken to the guy selling in the link above and he says he's also sold them to people saying they are for the gsxr4 and is happy to swap it if it don't fit, just have a measure before opening it.

You only need to check the hole centers.

Looking at the part number for the srad gasket its also the same gasket as the sv6, ape man says he's got loads of adjusters with different model numbers for different model bikes and they are all the same so in typical Suzi fashion they are using one fits all.

Thanks again VVS.

I tried calling a couple of times but no answer. I think i'll go ahead and order the APE tensioner and a gasket at the same time.

PolyMax delivery arrived today, so now its just finding the time to fit everything - Should probably wait until after my uni exams

Can't wait to get it running correctly and enjoy the nice(ish) weather

So nice little tip when fitting new orings is lubricate them with a little petrol, fitting dry can do them some damage.

You will find everything slides back in nicely.

Thanks for the tip, I'll make sure to use a little petrol to soak them in.

What I've realised I didn't mention is my bike has a yoshimura exhaust can on it.
Should this make a large difference?

I don't know yet if my needles have been adjusted or are on the middle notch as standard.

If the standard 1.5 turns out on the fuel screw and middle position of the needle doesn't work properly (poor idle or during revs) what would I change first?

Am I right in saying that moving the needle down a notch, would increase the fuel flow and make it richer? For an aftermarket exhaust, does the bike usually require a larger fuel flow?

Also, would turning the mixture screws out(anti-clockwise) cause a larger fuel flow as well?

I just want to have all the required information for when I come to doing the carbs as I know they are sensitive!

Thanks again

*Edit" - I now realise I had mentioned the yoshimura ( ), but would still appreciate information on what to do if it doesn't run correctly i.e. Mixture screw and needle notch position