Base gasket replacement (both cylinders) - Pics

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limeyduffa
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Base gasket replacement (both cylinders) - Pics

Post by limeyduffa » Sat Jun 23, 2018 11:53 am

This is a post about my base gasket replacement (both cylinders). A video will come later (particularly torquing and circlip install). For now, some pics.

Engine was bolted to a heavy 2nd hand coffee table. I'm glad I did this. The engine is able to sit on a flat surface by itself, but it is top heavy and can fall over. It took me ½ a day to make the table brackets - well worth it !. Probably quicker if I had a welder handy.
01_engine_on_table.jpg
Starter motor off:
02_starter_motor.jpg
03_starter_motor.jpg
Cam bridge off, front cyl:
04_cam_bridge_off.jpg
05_cam_bridge.jpg
Chain off:
06_chain_off.jpg
Removing bearing bolt. This is a bit tricky to remove. You have to get a screw driver on the timing gear and wretch it. I'll show it better in the video (hopefully the quality is good enough in the video).

When removing/inserting bearing bolt, be careful of the needle bearing inside the bearing bolt. Mine slipped off when I went to insert it, bounced off the coffee table corner and rolled 2m over the floor FFS :oops:
07_upper_chain_drive_out.jpg
All the bits..
08_head_bits.jpg
The top end with the bits removed:
09_head.jpg
Last edited by limeyduffa on Sun Jun 24, 2018 11:20 am, edited 6 times in total.

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Re: Base gasket replacement (both cylinders) - Pics

Post by limeyduffa » Sat Jun 23, 2018 11:57 am

Lifting the front cyl. As you can see, it just sits there. The piston is locked by the locking bolt (a special tool that locks the craft shaft).
10_head_removal.jpg
You remove circlip from one side only. There is a small recess/notch in the cylinder barrel where (presumably) KTM's special tool is seated. and oh yes, don't remove piston from barrel. The piston stays inside barrel when you remove head.
11_head_removal.jpg
12_head_removal.jpg
More bits:
13_all_the_bits.jpg
Inside the crank: I was worried about pitted surfaces, like what the ADV riders had reported on their 950 and early 990's. Mine (both cyls) had no damage (There is a post about an ADV rider bogging up his pits using liquid metal).
14_in_the_crank.jpg

The little end:
15_little_end.jpg
Rear cyl cams. Notice the colour coding:

Red: Front exit
Orange: Front Intake
Green: Rear intake
Orange: Rear exit
16_rear_cyl_cams.jpg
17_rear_cyl_cams_mark.jpg
There's a hole in my bucket, Dear Lizer.. stuffed buckets (intake, rear cyl)
18_surprise_stuffed_buckets.jpg
Last edited by limeyduffa on Sun Jun 24, 2018 1:36 am, edited 5 times in total.

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Re: Base gasket replacement (both cylinders) - Pics

Post by limeyduffa » Sat Jun 23, 2018 12:04 pm

Lifting rear cyl:
19_lifting_rear_cyl.jpg
20_rear_cyl_off.jpg
Rear cyl off:
21_rear_cyl_off.jpg
Stuffed bucket:
22_stuffed_bucket.jpg
The rear cams:
23_rear_exit_cam.jpg
Notice the line on the top cam. That is caused by the damaged bucket:
24_rear_intake_cam.jpg
Tappets and bucket remove/install:
25_tappet_install.jpg
26_bucket_install.jpg
Marked cam (rear cyl, intake):
27_marked_cam.jpg
The LC8 caught being the skateboarding punk that it is :P. Note: balance point of engine is approximately the drain plug. I'm doing it wrong:
28_LC8_skateboarding_punk.jpg
Overall, the 990 LC8 is an easy engine to work on. The tappet install isn't that scary. It can be done in less than a minute with needle plyers, a strong wrist and the knack.
Last edited by limeyduffa on Sun Jun 24, 2018 1:39 am, edited 1 time in total.

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Re: Base gasket replacement (both cylinders) - Pics

Post by limeyduffa » Sat Jun 23, 2018 12:45 pm

A few words on specials tools and parts.

All the head bolts can be accessed with a small 13mm socket, except for one. I brought a $22AUD 13mm 3/8" drive extension from TotalTools. I have a crappy torque wretch that is 20 years old and want to avoid changing the setting on the wretch every time I use the extension. Bad torque wretch torquing all nuts +/- 4Nm, not so bad. Bad torque wretch torquing nuts so that any nut may varying +/- 4Nm - bad. So I used a trick of setting the extension at 90 degrees. At this position, I set the torque wretch once and use that setting for all nuts (ie: no need to dial in corrected torque when using the extension).
torque_wretch.jpg
(In the pic above, you'll notice it's not quiet 90deg, but when I crank it, is gets closer.. so it's 90degish. Oh well, close enough. Better than the error introduced as discussed above).

The crank shaft locking bolt is a M8 x 100mm bolt I brought from Bunnings for about $2AUD. I ground down the end to about 60deg. I should have done it a bit shallower (maybe 30deg).. but it works okay. I used a phillips screwdriver to gauge depth of locking recess on shaft. I then put some masking tape on locking bolt so that I know when it bottoms out on shaft. Note: It's easy to look down the crank locking hole to locate the shaft recess (with a head torch).
locking_bolt.jpg
Instead of the expensive Motorex Calcium Sultanate Complex grease, I got exactly the same thing (same spec) from a local Chandlery at a fraction of the cost.
grease.jpg
Tips on the circlip, I will show it in my video. To remove, hold circlip with long nose plyers about here and pry out. Removal is very easy. There is a recess in the piston that allows you to put the nose of the plyers in and lever clip out.
circlip_remove.jpg
To insert, put hook into recess of piston, push left land side of circlip with left thumb and holding plyers in right hand, twist wrist (and plyers) anti-clock wise. A lot of force is needed. No good if you have lady hands and not sure how that will work with south-paws.
circlip_insert.jpg
The parts. These are for the front cyl:
29_parts.jpg
The gasket is metal, and coated with a black conform. It has a small bead of what looks like grease in one of the elongated recesses of the gasket. I replaced the head washers and nuts. I was going to replace the studs (I did order them), but changed my mind. The studs looked difficult to remove without special tools. One of the studs was frozen.

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Re: Base gasket replacement (both cylinders) - Pics

Post by eagle_awd » Mon Jun 25, 2018 2:20 pm

Thanks....This will come in handy for sure.

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Re: Base gasket replacement (both cylinders) - Pics

Post by limeyduffa » Tue Jun 26, 2018 11:09 am

No worries. I have a series of interstate trips over the next 2 months and waiting for more parts from England (the new buckets, an impeller etc). I may have the bike running in September. I'll let you know if I have blown it up :lol:

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Re: Base gasket replacement (both cylinders) - Pics

Post by linehand » Tue Jun 26, 2018 1:10 pm

Great write up, thanks for the info!

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