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jacko1959

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Guys This morning I have just reached rock bottom
My problem started when early this year I bought my tx650a from a fellow biker who I thought I could trust the engine turned out to be scrap and it lasted two days before it started blowing smoke out like a 2 stroke on full bore after it has poodled along at 30 for the last 10 miles.I striped the engine and took the barrels and pistons to be checked +50 rebore needed so orderd my pistons and rings from xs dealer 447 engine checked gudgen pin size yep 447 new jap kit arrived.Now today I finally have all the bits to rebuild so after reading and looking at everthing on this site I start to rebuild.Got pistons into jugs fitted new cam chain now find top dead centre oh top piston rings pop out at the top.Check forum starting to get worried get piston rings back into jugs and decide to put head on first ;) put the 2 bolts in next to sparkplug holes now turn engine to find top dead centre problem it lifts the whole lot from the crankcase.Now Im sweating like a pig :yikes:
Pulled it apart again took one of the pistons of the crank got one of the old pistons put them side by side like I did when they came yep same size then I saw my megga mistake the gudgen pin hole if you line them up together the new pistons are a good 5mm higher how can this happen I was so carefull ordering parts .
Im totaly gutted I have spent a fortune as you guys will know and understand .
 
Sounds like you have a european spec, 533 engine, long rod motor. the 533 rods are 10mm longer so the gudgeon pin hole needs to sit 10mm higher in the piston.
Although it is possible someone installed a 533 crank into a 447 block.
https://xs650forum.proboards.com/thread/324

This vender enjoys an excellent quality reputation. Shipping times with the virus may be an issue.
https://www.cruzinimage.net/2017/12...ro-engine-0-5mm-oversize-pistons-set-75-50mm/

I would think Heiden Tuning has what you need in stock.
https://www.heidentuning.com/xs650-...rsize-0-50-price-for-1-piece-only-detail.html
You should not a have problem finding a new home for the pistons you have now as so many US spec bikes have been imported to europe.
 
Last edited:
3_stock_rods copy 1.jpg
 
Hi Gary
I dont get it mate the engine block is 447 the cam has 447 stamped on it and the dealer who sold me the pistons told me it was 447 because of the gudgen pin size.My bill from him says xs650 447piston kit.japan .
 
The 533 rods have the same gudgeon pin size as the 447, the only difference is the rods are 10mm longer.
Hot rodders feel the longer rods offer a performance advantage.
The older 70-73 256 motors used the larger 22mm pins.
 
Then per Skull's chart it is a 1975 533 rod motor. A european dealer should have been sharp enough to have you check the rods for the 533. Perhaps he will work with you on getting the correct pistons.
 
Its a 75 XSB 553 long rod motor...........Production year is Aug to July......Those months are not set in stone but a bike built from Aug 74 with the vin no starting from 500101 is a 75XSB
 
jacko1959 said:
Guys This morning I have just reached rock bottom
My problem started when early this year I bought my tx650a from a fellow biker who I thought I could trust the engine turned out to be scrap and it lasted two days before it started blowing smoke out like a 2 stroke on full bore after it has poodled along at 30 for the last 10 miles.I striped the engine and took the barrels and pistons to be checked +50 rebore needed so orderd my pistons and rings from xs dealer 447 engine checked gudgen pin size yep 447 new jap kit arrived.Now today I finally have all the bits to rebuild so after reading and looking at everthing on this site I start to rebuild.Got pistons into jugs fitted new cam chain now find top dead centre oh top piston rings pop out at the top.Check forum starting to get worried get piston rings back into jugs and decide to put head on first ;) put the 2 bolts in next to sparkplug holes now turn engine to find top dead centre problem it lifts the whole lot from the crankcase.Now Im sweating like a pig :yikes:
Pulled it apart again took one of the pistons of the crank got one of the old pistons put them side by side like I did when they came yep same size then I saw my megga mistake the gudgen pin hole if you line them up together the new pistons are a good 5mm higher how can this happen I was so carefull ordering parts .
Im totaly gutted I have spent a fortune as you guys will know and understand .
Click to expand...

I have the same problem, I’m rebuilding a 447 engine, I ordered a set of 447 pistons plus .5mm oversize, got the barrels bored and started assembly, dropped the barrel on , turned the crank and the pistons protruded around 10 mm above the mating face of the barrel. I’ve now found out that the rods are stamped 533, someone has obviously changed the crank in the past.
I’m now trying to figure out which pistons I need to reorder,any help gratefully received.
 
I think most of if not all the European bikes got the 533 rods. If your bike was originally sold in Europe I would assume it has the 533 rods and pistons.
If your in Europe and your bike was imported from the US then assume it has the 447 rods and pistons.
If your pistons are coming up out of the cylinders when finding TDC then you have two options. Either swap the pistons you have for the right ones, this is the easy fix or do it the hard way and swap the 553 rods for 447 rods.
Perhaps the person you bought the pistons from wasn't clear on where your bike came from. I see no reason he shouldn't swap them for the right ones. It's his fault as much as yours. Being a parts seller he should have made sure which pistons your bike needed.
Hope you get it settled.
It may be a lot of cash outlay, but once done you will find it should run great for many years of pleasurable riding.
Leo
 

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