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Belt change on DB5R - tiny tools and tiny fingers

 
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CBR_DBR



Joined: 19 Sep 2015
Posts: 21
Location: Canberra Australia

PostPosted: Sat May 13, 2017 2:27 pm    Post subject: Belt change on DB5R - tiny tools and tiny fingers Reply with quote

Hi All,

I decided to change the belts on the DS1100 engine of my DB5R because they are three years old and the bike hasn't run much at all over the last year. Sad

First of all, I need to get the spark plugs out so I can rotate the crank a bit easier. Horizontal cylinder comes out easy with a 16mm deep socket. Vertical one: not so much. The socket fits all right but the 1/2" drive doesn't fit next to the frame rails. Went and bought a 16mm socket with 3/8" drive and now the plug is out.

With the plugs removed, lined up the timing marks on the crank pulley and the mark on the cam pulleys with the marks... no marks on the heads whatsoever! (By the way, the lovely flywheel cover on the Bimota doesn't let you see the marks on the flywheel.)

Made some marks on the plastic behind the belts that line up with the dots on the pulleys, That way I would have at least some reference points when the new belts went back on. Marked the belts so I'd know how to put the new ones on.

Time to remove the old belts. The horizontal cylinder is at TDC so there should be no issue with the cam moving. All the how-to's I read and videos I found on YouTube said that the vertical might move a bit, but you 'just turn that back' when you put the new belt on. No problem.

Well it is on a DB5! The cam pulley on the vertical cylinder is right behind a frame tube. Even if you have tiny fingers (which I don't) there is no way you'll get to the pulley, rotate it against the force of the 'helper' springs and keep it there while you fiddle the new belt on.

Loads of people claim you don't need a cam locking tool for the 2V engines. Well, I decided to wuss out, save the skin on my knuckles and get myself a cam locking tool. But when I looked at the images of the Ducati ones I thought I'd have a stab at making one from an M8 bolt. All it needs the end of the bolt (15mm) to be reduced to a diameter of 6mm. I don't have a lathe (nor the skills to use one) but I figured I'd have a go with the Dremel and a grinding wheel.

It's not as straight as I'd like it to be but it works! Screws in through the hole in the other side of the vertical head and engages with the slot in the cam wheel to keep it in place. Now the vertical belt went on without a problem and the horizontal one soon followed.

All I need to do now is to tension them properly (going to try the frequency method), finish installing the Motolectric kit for the starter circuit and fire her up!
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brian



Joined: 22 Aug 2011
Posts: 2491
Location: QLD, Australia

PostPosted: Sat May 13, 2017 11:18 pm    Post subject: Reply with quote

Nice to see the DB5r getting some TLC Mike. I didn't even attempt to do the belts on my DB4 without dropping the engine out. I got the valve clearance done while it was out as well. I put a love,y set of carbon belt covers on the DB4 but alas, they can't even be seen with the bodywork on Crying or Very sad

Getting cool in Canberra by now I guess?
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Current rides - '99 Bimota DB4, '96 Bimota SB6, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250,
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quikduk



Joined: 13 Aug 2016
Posts: 169
Location: Southern California, USA

PostPosted: Sun May 14, 2017 7:30 am    Post subject: Reply with quote

CBR_DBR,

So in order to screw in the modified 8mm bolt, do you take the cam cap off?

I never had to do that on my 750ss but it didn't have the frame clearance issues the Bimotas have.

I don't have to do mine on the DB6 for a bit as the prior owner just had them done. BTW, how long are they good for mileage wise? I haven't looked at the service manual in ages but just curious.

I used to do my belts and valves every 5K religiously on the 750 but it had a highly strung motor.

Re: the tension, I am used to the 5mm hex key test but have downloaded tuner apps to my iPhone to try the next time.

Let us know the method you chose and how it went when you finish yours.

Best regards,

Quikduk
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CBR_DBR



Joined: 19 Sep 2015
Posts: 21
Location: Canberra Australia

PostPosted: Mon May 15, 2017 12:33 pm    Post subject: Reply with quote

Hi Brian,

Why do we do this again? Smile

And you're right about the temperature: It's getting pretty chilly at night in Canberra at the moment!

Mike
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CBR_DBR



Joined: 19 Sep 2015
Posts: 21
Location: Canberra Australia

PostPosted: Mon May 15, 2017 1:16 pm    Post subject: Reply with quote

Hi Quikduk,

You don't have to take the whole cap off. All you need to take out is a stubby M8 bolt that is screwed through the cap. You line up the timing mark on the crankshaft pulley with the mark on the engine casing. The hole in the cam is now right behind the opening of the bolt you took out. Screw the modified M8 bolt in and its 6mm end engages with the hole in the cam to fix it in place.

As you may know, there are a lot of different opinions about the life span of the belts. Ducati say 2 years (or 15,000 kms?) but for newer models it is now 5 years. There are stories around from people who have used belts for many years without problems. A very knowledgable mechanic here in Oz (Brad the Bike Boy) has written some interesting articles on the topic (http://bradthebikeboy.blogspot.com.au/2017/02/ducati-timing-belt-failures-and.html

I choose to believe that the materials of belts has improved but that I'd rather spend $100 on belts than $1000s on new heads and pistons. This is why I replace them every 2-3 years. If I don't know when they were done (like with the GT1000 we bought recently for my partner) I'll replace them regardless.

Yesterday I tensioned the belts using the frequency method but I've hit on bit of a weird issue. I tensioned the vertical belt and get 100Hz exactly when I pluck it. Out of interest I also tested with the 5mm/6mm Allen key method and it seemed spot-on. When I did the horizontal cylinder I got another 100Hz reading but the belt is tighter than the vertical one. A 5mm Allen key definitely doesn't fit between the belt and the fixed roller. I don't want to run the belts too tight and damage the bearings so I will loosen it a little and run with the Allen key method to test the tension.

I still want to find out what causes the difference in tension when the frequencies are the same, though. It seems the frequency measurement should be the more accurate one. I've made sure I check the tension when the respective cylinders are at TDC so I can't really explain it yet.

I'll have a bit more of a play to try and figure this out.

Mike
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Admin
Site Admin


Joined: 22 Oct 2007
Posts: 491
Location: Stafford, UK

PostPosted: Thu May 18, 2017 10:53 am    Post subject: Reply with quote

Hiya

Belt life probably varies with a lot of factors. Bikes tend to use narrower belts and smaller pulley wheels than cars, both of which will give them a harder life. Plus bikes probably get left standing more often.

CBR_DBR wrote:
I still want to find out what causes the difference in tension when the frequencies are the same, though. It seems the frequency measurement should be the more accurate one. I've made sure I check the tension when the respective cylinders are at TDC so I can't really explain it yet.


Are the pulley whhels in the same respective positions on each cylinder? Just wondering in Ducati moved the tensioner on one a few mm along (packaging reasons maybe)

All the best

Katy
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polyesterpig



Joined: 30 Jan 2011
Posts: 49
Location: California USA

PostPosted: Mon Nov 20, 2017 3:33 am    Post subject: Reply with quote

The 1100 evo Ducati motor (similar to the 1000ds motor) belt tension is totally different than the prior Ducati belt tensions. I have the Ducati mathesis tool and tensioned my 1100 Ducati evo engine to 110 Hz (both cylinders). I decided to check them with the Allen key method. The vertical cylinder would only pass a 4mm Allen key on the stationary roller, but the horizontal cyclinder would only pass a 1mm feeler Guage on the stationary roller. So your first settings were probably correct. The locations of the rollers are not the same on the 1000/1100 vertical and horizontal cylinders, thatís why you canít use the old 4mm method on the horizontal cylinder. Hope this helps.
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