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Re: So you want to rebuild a 1st Gen 1100 shock (Pt.1)

Cheer Andrew, Indeed it does sound like a way more streightforward approach.

Step away from the 25yr old shock...
 

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Re: So you want to rebuild a 1st Gen 1100 shock (Pt.1)

Hey I just spotted this: http://www.motosport.com/motorcycle/oem-parts/SUZUKI/1986/GSXR750G/REAR-SHOCK-ABSORBER

I note in the threat that the 750 shock is a sealed unit and can't be rebuilt and i also note that I'm enough of a muppet on the spanners not to know whether any of the parts listed definately live inside the unit (some obviously don't - I'm not the fish juggler), but is it possible the shock can be rebuilt? Also, this supplier has the '86 Ltd shock available - http://www.motosport.com/motorcycle/oem-parts/SUZUKI/1986/GSXR750R/REAR-SHOCK-ABSORBER but for 1300 kiwi rupees I could probably find a new Ohlins..
 

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Re: So you want to rebuild a 1st Gen 1100 shock (Pt.1)

Nope, that's a sealed unit... I know a guy who drilled a hole in the bottom, replaced the oil and said it was awesome but I don't really think it was the right approach for rear suspension on these bikes.

The OEM shock is really junk and looses control when it heats up which doesn't take long. I put in an Ohlins that I picked up from the Classifieds. They don't come up too often these days but there were two for sale last month and I think they sold for about $500 USD. List for the Ohlins was $1,200 but I see them on EBay or our classifieds for about half price. I bought mine brand new for around $600 a couple of years ago and there is no comparison with the factory 750 unit.

I have an R1 shock too and if I didn't have the Ohlins, it would be in my bike. R1 shock costs about $50 through Craigslist/Ebay. Also Fox and WP made shocks for our bikes.... They show up every now and again on EBay.
 

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Re: So you want to rebuild a 1st Gen 1100 shock (Pt.1)

I'll put on my list turning the entire write-up with pictures into a PDF also, that way it can be easily downloaded and printed.
 

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Re: Understanding Carbs

Referecnce #37 idle screw o-rings.
As of July 2012, I just got the small o-rings from my suzuki dealership near Cincinnati, Ohio. They had to order them, 4 days @ $3.50 a piece. No luck at hardware stores before that.
 

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Re: Understanding Carbs

I am in the process of rebuilding a set of the BST36SS carburetors and I have noticed the outside slide springs are longer green springs and the inside slide springs and an inch shorter. I couldn't believe this was correct but the suzuki parts site shows two different sets of spring part numbers. Does anyone now why this is or how it possibly works correctly?
 

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Re: Understanding Carbs

Lots of really good information on here. Looking for some feedback on what my best overall choice would be for my 1989 with a 4:1 Vance and Hines exhaust:

1. 38mm Mikuni Flat Slides, K&N Air Filter (no air box)
2. 38mm Mikun Flat Slides with Air Box. I have heard mixed reviews on whether this would work with Flat Slides but others that say it does work and the carbs run more stable
3. Original CV Slingshot Carbs with K&N Air Filter (no box)
4. Original CV Slingshot Carbs with air box

For esthetics I really like the look of the K&N pod filters but have heard the bike runs much better and more stable with the air box.

Any input is greatly appreciated.
 

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Re: Understanding Carbs

REASSEMBLY-

Now that all the carbs and jets are clean, you can put them all back together. Its pretty much the reverse of taking it apart but theres some things to know.

*When putting the vaccum caps or float bowls back on i would reccomend replacing the phillips head screws with socket cap screws, especially if you're putting a jet kit in. If you have the carbs apart multiple times to change the settings, the head of the screw usually strips out. The size of the screw to replace them is 8mm x 1.25. Go to your local hardware store and get some stainless steel screws and lock washers. If all they have is regular steel thats ok, but they will rust as you can see mine did in the pics. You should only need lock washers for the float bowls. Remeber to take the screw with you so you can get the correct length.


Order of re-assembly (read all information below before re-assembly):

1. Plastic guide for slide and emulsion tube

2. Jets (install main jet first to hold emulsion tube in) then all other jets

3. Needle/slide/diagphram assembly

4. Slide spring

5. Vaccum caps

6. Float assemblys (then set float height)

7. Float bowls

8. Re-install carbs on bike



Plastic guide/Emulsion tubes - When putting the emulsion tubes back in, there is only one way they can go back in. If you look at the bottom of the tube ( in the pictures )you can see a slot. Now look at the main jet tower on the carb, see that pin? ( Im pointing to it in the pics ) This is where the slot in the tube needs to line up. If the tube doesnt go in easily (might have to lightly tap them in) then the tube is probably not lined up right.

Make sure when installing the slide guide block the o-ring is centered and not off to one side.

Needle/Slide/Diaphram assembly - The needle and washers go in the order shown in the picture, the white washer that goes on bottom has two notches cut into it. These notches face down.

Vaccum caps and slide springs - Make sure the o-rings are in place before you install the vaccum cap. If not there will be a vaccum leak and the bike will not run right. When installing the vaccum cap, put the slide spring onto the tower in the cap and then lower both onto the carb. If you put the spring in the carb first and then lower the cap onto the spring, it might not seat correctly and may come off the tower. After you have all the caps on, manually work the slide with your finger, it should slide up and down with some resistance. If it slides up easily, or doesnt feel right, the spring may have popped off the cap. Take the cap off again and double check everything.

Pilot screws/Jets - As you can see in the pic, the o-ring goes first, then spring, then the screw. Screw the pilot screw in until you feel it bottom out on the carb. Do not tighten the pilot screw anymore after it has bottomed out! You may damage the screw or could damage the carb. Now back the screw out however many turns that are factory reccomended. If you have added a performance exhaust or air filter you may need to turn the screw out farther to richen up the idle mixture. The more you back out the pilot screw (counter-clockwise) the richer the idle mix. The more it is screwed in (clockwise), the leaner the idle mixture.

The pilot air jets that screw into the mouth of the carb (airbox side) are easy to crossthread so just be careful.


Float - Once all the jets are in, its time to put the float on. I put some clean motor oil on my finger and lightly coat the o-rings. The oil will help the float "snap" into place and will prevent you from breaking the float from forcing it into place. The 0-rings are what holds the float assembly to the carb. It is an interference fit. After putting the float assembly on, lightly pull up on each end of the float where the o-rings hold it. If you can easily pull the float back off the carb, the o-rings are no good and need to be replaced.

Setting Float Height - Now that the carbs are pretty much all back together and the float assemblys are on you need to set float height. The carbs should be leaning at an angle so that the float tang (metal tab that rides on the needle) is touching the needle but not compressing it. I myself pick the float up off the needle and then set it down gently to make sure the needle wasnt compressed to begin with. Now you need to know what the float height spec is. You can refer to the specs in the beginning of this sticky or look in your repair manual. The spec will be in millimeters. If using vernier calipers you will need to convert millimeters to inches. You can use this webpage to do your conversion, http://www.sciencemadesimple.net/length.php. To adjust the float height you will need to bend the float tang either up or down. The float tang is the piece of metal that the needle clips to on the float assembly. Bending it up will decrease the float height, bending it down will have the opposite affect.

One thing to mention that i have seen is that not all float tanks are the same height. What i mean by this is on one float assembly , one float tank may be higher than the other one. When setting float height you will want to set it on the float tank that is highest. I should have taken a picture to demonstrate this but i didnt think of it until after i had the carbs back on my bike.


NOTE- Its called setting the float height but your actually setting the fuel level. Picture the carbs installed on the bike, the higher the float is, the higher the fuel level is in the bowl. The higher the fuel level the richer the air/fuel mix. The lower the fuel level, the leaner the air/fuel mix. The reason for this is, the closer the fuel is to the venturi (emulsion tube and needle) the easier it is for the vaccum to pick up the fuel. The farther away the fuel is, the more vaccum (higher rpm) you will need to pick up the fuel.

Some float heights converted:
13mm = .0512
13.6 = .0535
14mm = .0551
14.6mm = .0575
15mm = .0591
16mm = .0630
17mm = .0669

You dont need to use a set of calipers, just as long as you measure from the base of the carb where the float bowl gasket sits to the very top of the float bowl with some type of measuring device. (As shown in picture)















Very nice explanation, hats off to your efforts man ! I just got my 88' 750 slingshot restored and now it ain't crossing even 130kmph. That got me here. looks like I m gonna have to open the carbs again !! dam !!
 

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Re: Understanding Carbs

Drawing of spacer with dimensions, its the little things that can make big differences sorry about quality of pics


Hello! First time poster so sorry for any mistakes. Saw this mod a few months back on OSS, and was planning on carrying it out when carbs next off. Decided recently that the time was right, but OSS is now broken so my bookmarks are useless. Was chuffed to find it mentioned again on here, but all the details are links to the OSS pages which don't work.
Just wondering if you could repost the info on here, or if you could point me in the right direction if it can be found anywhere else.
Thanks a lot, Mat

edit - I see the mod info is now showing on here. Looks like oldskoolsuzuki is alive again. Thanks a lot bud - you're my hero!
 

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Re: Understanding Carbs

Just tore down my carbs, everything bagged and tagged cept one stubborn pilot air jet, thinking of using a screw extractor but then it will be toast after removal, guess my worry is, can you still get all the jets and or parts that are either damaged or worn for these carbs, my is out of an 86.
 

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Re: Understanding Carbs

Hi Jonny, sounds like your spacers are just what I need as my carbs seem to wear the needle jets out pretty quickly as well.

Would you be able to post up the drawing again as the links gone.

Cheers.
 

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Canadian 86-88 1100

Mikuni 34 mm bst ss carbs on 86-87-88 Canadian 1100 models have U.K. specs.

So if you own a 86-88 Canadian 11 I suggest checking the parts before ordering.

I thought that mine had the same spec as U.S. but didn't.

GSX-R1100

1986-1988

Type: BST34SS

Main Jet: 130

Main Air Jet: 0.6mm

Jet Needle
*U.K: 4D13-3
U.S: 5D29

Needle Jet
*U.K: O-9 "537"
U.S: P-2

Pilot Jet
*U.K: 42.5
U.S: 32.5

Pilot Air Jet
*U.K: 150
U.S: 135

Pilot Screw setting
U.K: Preset (2 turns out)
U.S: Preset

Starter Jet (choke): 45

Float Height: 14.6mm (+/- 1mm)
 

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Borrowed Mikuni CV Tuning Guide

***CV Carb Tuning from the Mikuni Manual***​



Follow steps in order:

1. Top end (full throttle / 7.5k to redline) - Best Main Jet must be selected before starting step 2! Select Best Main Jet to get the best, most even top end power (full throttle/after 7500 rpm), select the main jet that produces the highest top speed / pulls hardest at high rpm:


a. If the bike pulls harder at high rpm when cold and less hard when fully warmed up, the main jet is too large. Install a smaller main jet and retest until you find the main jet that pulls the hardest at high rpm when fully warmed up. This must be done first - before moving on to the other tuning ranges.

b. If the bike doesn't pull well at high rpm when cold and gets only slightly better when fully warmed up, the main jet is too small. In order to properly tune the midrange and low rpm carburetion, THE MAIN JET MUST FIRST BE PROPERLY SELECTED after 10 to 15 minutes of hard use! Do not pay too much attention to the low end richness when you are changing main jets - you still need to be using the main jets that produce the best power at high rpm. You will deal with the low end / cruise later - after step 2.

2. Midrange (full throttle /5k-7k). Select best needle clip position to get the best power at full throttle / 5k-7k rpm, after you have already selected the best main jet:


a. If the engine pulls better on a full throttle roll-on starting at <3k, when cool but soft when at full operating temperature, it is too rich in the midrange and the needle should be lowered.

b. If the engine pulls better when fully warmed up but still not great between 5k-7k, try raising the needle to richen 5k-7k.

If the engine pulls equally well between 5k-7k when cooler as compared to fully warmed up, the needle height is probably properly set. Do not pay too much attention to the low end richness when you are changing needle clip positions - you still need to be using the clip position that produces the best full throttle / 5k-7k power in conjunction with the main jets that produce the best power at high rpm. You will deal with the low end / cruise next.

3. Low end (full throttle / 2k-3k) Float height (AKA fuel level & how to..)
To get best low end power, set float height so that the engine will accept full throttle in 2nd gear from 2.5k to 3k rpm at minimum. Float heights, unless otherwise specified in the installation guide, are measured from the "gasket surface" of the carb body to the highest part of the top of the float - with the float tang touching but not compressing the float valve spring.

Base settings are usually given if a particular application has a history of fuel level criticalness. The Fuel level height in the float bowl affects full throttle/low rpm and, also, richness or leanness at cruise/low rpm. Reference: a bike that runs cleanly at small throttle openings when cold, but starts to show signs of richness as it heats up to full operating temperature, will usually be leaned out enough to be correct if the fuel level is LOWERED 1mm. Check out and RESET all: Suzuki (all), Yamaha (all) and Kawasaki (if low speed problems occur). Needless to say, FUEL LEVEL IS EXTREMELY IMPORTANT!!!

If there are low end richness problems, even after lowering the fuel level much more than 1.5mm from our initial settings, also check for needle wear and needle jet (part of the emulsion tube). See Worn Needle and Worn Needle Jet diagram. It is VERY common for the brass needle jets (in the top of the "emulsion tube") in 36mm, 38mm and 40mm Mikuni CV carbs to wear out in as little as 5,000 miles. Check them for "oblong" wear - the needle jet orifice starts out round! Factory Pro produces stock replacement needle jets / emulsion tubes for 36mm and 38mm Mikuni carbs.

4. Idle and low rpm cruise. Fuel Screw setting (AKA mixture screws)
There is usually a machined brass or aluminum cap over the fuel screws on all but newer Honda. It's about the diameter of a pencil. Cap removal details. Newer Honda carbs use a special "D" shaped driver, usually supplied in the carb recal kit. Set mixture screws at recommended settings, as a starting point.

For smoothest idle, 2nd gear 4000 rpm steady state cruise, and 1/8 throttle high rpm operation: Pilot fuel mixture screw settings, float level AND pilot jet size are the primary source of mixture delivery during 4000 rpm steady state cruise operation.


a. If lean surging is encountered, richen mixture screws (turn out) in 1/2 turn increments. Alternative pilot jets are supplied when normally required.

b. Pilot fuel mixture screw settings, float level and pilot jet size also affect high-rpm 0 to 1/8 throttle maneuvers. B. Too lean, will cause surging problems when the engine is operated at high rpm at small throttle openings! Opening the mixture screws and/or increasing pilot jet size will usually cure the problem. NOTE: A rich problem gets worse as the engine heats up.

c. If the throttle is lightly "blipped" at idle, and the rpm drops below the set idle speed then rises up to the set idle speed, the low speed mixture screws are probably set too rich: try 1/2 turn in, to lean the idle mixture. NOTE: A lean problem gets better as the engine heats up.

d. If the throttle is lightly "blipped" at idle, and the rpm "hangs up" before dropping to the set idle speed, and there are no intake leaks and the idle speed is set at less than 1000 rpm, the mixture screws are probably too lean: try 1/2 turn out, to richen the mixture. Be sure there are no intake leaks and the idle speed is set at less than 1000 rpm!
 

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Re: Understanding Carbs

i saw this on the first page. what are these measured by? mm?? in??
1985 through 1987 U.K

Type: VM29SS

Main Jet: 97.5 <-measurement?

Main Air Jet: 0.5mm

Jet Needle: 6DP-2-3

Needle Jet: P-5

Pilot Jet: 32.5 <-measurement?

Pilot Air Jet: 1.6mm

Pilot Screw setting: Preset (1 1/2 turns out)

Starter Jet (choke): 42.5 <-measurement?

Float Height: 14.2mm (+/- 1mm)
 

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Re: Understanding Carbs

Hi, first post here at this site...
Struggling with my -92 GSX-r 1100 Devil 4-1 K&N and german edition of the bike,
50 000 km on the meter.
I got it working with changing MAJ, PAJ and MJ.
I changed standard Pilot Air Jet and Main Air Jet, i had to drill all of them out with a 3,3 mm drill and made new M4 threads. I´m usig the stock 40mm Cv carbs and using 152.5 main jet and MAJ and PAJ both 1.0 jets.
 

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Re: Understanding Carbs

Hey guys great thread, lots of useful info.
I've juts bought a GSXR750J with 63000kms on it. It hasn't been started in around 3 yrs & came from a very hot climate.
The carby's are siezed as in the butterflys wont turn & a couple of the slides won't go up either.
I've pulled the tops off as well as the float bowls & had them soaking in a mixture of water, baking soda, white vinegar & dishwashing detergent for about a week but still no movement.
Any suggestions would be appreciated. Cheers.
 

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