1981 GSX1100 Katana Based Project

[Shin-Ken 1074]

Hoping the weather is fine at some stage over the weekend so I can take the DW on test ride with the latest main jets that I installed this week. I noticed an oil weep around the oil sensor plate, checked the plate while the carbs were removed and sure enough the oil pressure o-ring and oil sensor plate o-ring were past their prime. Bought new o-rings, sealing washers and bolts for the plate. Installed the new seals so that should take care of the oil weep issue.

Latest main jets installed.
Main jet by Max Mutarn, on Flickr


Oil sensor plate
Oil press sensor 2 by Max Mutarn, on Flickr


Oil sensor plate by Max Mutarn, on Flickr

Old vs new oil pressure sensor o-ring.
Oil pressure sensor o-ring by Max Mutarn, on Flickr


Old vs new oil sensor plate o-ring.
Oil sensor plate o-rings by Max Mutarn, on Flickr

Latest main jets installed and oil sensor o-rings, bolts and seals replaced, now just waiting for a fine day.

[Shin-Ken 1074]

One of these days I'm going to try a jet change with the carbs still installed on the engine. It'll take patience but I think I can do it. The stock airbox/airfilter on these bikes is a hassle for sure.

Yeah, totally agree with you on that one, carbs off, carbs on with the stock airbox is no fun at all! Changing the main jets with the carbs in place is doable and as you say patience is the key when doing it that way. A short shank angled blade screwdriver made to length would be helpful. Another thing that would be helpful in future, is once the fuel bowls are removed, swap the fuel bowl screws for allen head bolts, much easier to remove the bowls and re-fit with an allen key in the restricted space rather than with a stumpy screwdriver.

[Shin-Ken 1074]

At last, a fine sunny day! Took the DW out for a test ride with the latest main jets and the 02 sensor numbers are looking pretty good.

From idle at 12.7 through the 5 throttle settings to WOT at 13.2, not perfect but pretty close. Speed readings for 40 kph, 60 kph, 80 kph and 100kph are all 12.4.

Throttle is crisp with instant power in all gears and no lag at all. Made some minor suspension adjustments and set the front tyre pressure at 34 PSI and the rear at 40 PSI. Steering is light and very responsive with minimal input needed to turn or change the riding line when deep into the corner at any speed. Suspension front and rear is smooth and handles bumps and uneven surfaces so well there is no need to try and dodge the road bumps. So carbs and suspension are now sorted. Next job is to install the oil cooler.

[Lorenzo]

Dunno, Captain America had no front brake; that's what I call some serious weight savings...

[GSX1100 dreamn]

What are you doing with these two sensors.

sensor.jpg

Cheers Andrew.

[Shin-Ken 1074]

Hi Andrew, your eagle eye has spotted the two oil temp sensors. The OEM sensor on the block is not connected to a read out (1135 clocks not being used) so I have installed a temporary (the red sensor in the pic) oil temp sensor and digital readout to monitor oil temps during the bedding in period. The extra weight of the red Yoshi sensor will be removed once everything is sorted out.

Cheers.

[GSX1100 dreamn]

Progress 1 or 2.

I found the inlet cam plug to give the most accurate engine temp in a sort of way. The oil temperature readings and and my 1250 CT readings were like for like at this position.

[Shin-Ken 1074]

Progress 1, using the port closest to the oil pump for the temp readings.

oil temp 1 by Max Mutarn, on Flickr

[Shin-Ken 1074]

With more ride time on the DW I am now getting a better feel for how I want to set things up, like last week with the suspension and tyre pressure. Next on the list is how I want to position the bars. The clip-ons are an aftermarket two part system with the bar using a spline to engage the clamp with a single bolt that not only clamps the bar to the fork leg it is also allows the bar position to be adjusted by repositioning the bar on the spline, simple, effective and most importantly, light!

The bars have been rotated up and forward and so far so good. Bars position adjustment is fast and easy and can be done on the fly as long as I remember to pack the 12 point socket in the tool roll.

The 12 point bolt in the pic locks the splines of the bar and clamp together as well as clamping the bar to the fork.
Aftermarket moly clip-on by Max Mutarn, on Flickr

[Shin-Ken 1074]

The adjustable bars with their original steel allen bolt and showing the spline adjustment before painting them and swapping the allen bolt for a titanium bolt.

Bars 1 by Max Mutarn, on Flickr


Bars 2 by Max Mutarn, on Flickr

[Shin-Ken 1074]

How the adjustable clip-ons look in the raised and slightly forward position, a bit flat bar looking but nothing wrong about that.

Clip on 1 by Max Mutarn, on Flickr

[Shin-Ken 1074]

There I was happy as a clam after dialing in the carbs and getting the Kat running oh so good and then, I get asked, "How would you like to fit a set of Mikuni 38mm flat slides to the DW?" I have ridden Kats with 38 mm flat-slides and WOW, they are a weapon!

With the time and effort invested to set up the 36mm CV carbs I was reluctant to think about starting over again setting up the flat-slides however, they are a good mod for the 1135 engine so Iam leaning towards going with the flat-slides. They weigh more than the 36 mm CV's but there are some mods that will reduce the weight by a few grams. Hhhhmmmm, ah why not, I think I'll give the flat-slides a go.


Mikuni 38 mm flat-slides
38 mm Flatslides by Max Mutarn, on Flickr

[steve murdoch]

Another chapter in this epic journey. Excellent!

https://www.orientexpress.com/Images/document/large/Mikuni-rs-manual.pdf

[Shin-Ken 1074]

Another chapter in this epic journey. Excellent!
https://www.orientexpress.com/Images...-rs-manual.pdf

Hi Steve, it will be awhile before the RS flat slides are installed, need to sort out super light weight spun aluminium velocity stacks, twin cables and switchblock throttle before the carbs can be bolted on. I am hoping this chapter will be shorter than it was setting up the 36mm CV's, now that was epic working through six jet sizes until hitting the sweet spot.

Thanks for the link to the RS specs and application chart, that will be helpful as the carbs I am buying are just the carbs, no chart included.

For now the oil cooler is still waiting to be installed so I am trying to get that finished later this week after I have finished replacing a radiator in a home vehicle.

[Shin-Ken 1074]

Swapping the 36mm CV carbs for 38 mm flat-slide carbs will help with performance but they will also add a few extra grams to the build so time to start looking at swapping or modifying parts to off-set the weight gain with the 38 mm flat-slides.

The first part that will be swapped is one that I look at everytime Iam on the DW, the front master res. Found a Brembo res that is lighter, uses a smaller bracket and much smaller bolt, should save around 110 grams not including the brake fluid. The original res was for the large single piston calipers that have been swapped for modern small diameter twin piston calipers so there is no need to lug around all that extra brake fluid. This is one time when small is better.

Front brake 1 by Max Mutarn, on Flickr


Front Brake 2 by Max Mutarn, on Flickr


Front brake 3 by Max Mutarn, on Flickr