Yamaha IT490/YZ490 Engine Rebuild & Decompression Valve

[@lokom18]

yeah! lucky me! two new videos with IT to watch! thank you!

[@KeepitBigBore]

More on the way 👍🏽

[@seank404]

Have the same bike same troubles.. got a machinist to bronze bush the Kickstarter hole (both) turned out lovely! Great for peace of mind! Great video thanks!

[@seank404]

Any chance you would rebuild my it465?

[@KeepitBigBore]

Thank you!! The bronze bush is a good job alright, you can even re centre the hole when boring it out as well to avoid the kick start gear rubbing the inside of the engine case!

[@KeepitBigBore]

I can do yes! If you have Facebook or Instagram you can message me, if you want to send any pictures it’s also keepitbigbore 👍🏽

[@markaddy53]

nice job lad cant wait to hear it fire up all the best 4 2022

[@KeepitBigBore]

Thank you! Happy new year 👍🏽

[@Kyle-rk8bw]

Can’t wait to hear it fire. Amazing work and attention to detail as always! That’s a bummer on those titanium cylinder studs

[@KeepitBigBore]

Thanks mate, you and me both!! I know, who would have thought?! At least I know everything not to do for my yz490 restoration now 😂

[@peterwall9896]

My iit was one of only five in the UK . I now have the BMW GS 1200 and the land rover defender not bad for an old man 😎👍👍👍👍

[@KeepitBigBore]

Were they that rare?? 😲I know the it465 was a popular bike! If a man has a defender and a GS1200 and he’s not happy then he’ll never be happy 😆 😂

[@peterwall9896]

@@KeepitBigBore my wife says I have too many projects and just sold husqvarna SM490

[@peterwall9896]

@@KeepitBigBore latest project is my log burner in the workshop it's lovely

[@KeepitBigBore]

Can’t beat a well heated workshop can you? takes half a day to warm up all the cast iron in my lathes and milling machine. Once it’s warm it stays warm all night!! 😬

[@seank404]

This vid is gold

[@lifes.projects]

The Boss..... 🤣 Great build that mate 👍

[@KeepitBigBore]

Thanks mate!! She’ll look well on the back of my defender 😬

[@benmaria9359]

Looking forward to hearing it bud, gonna sound dam good!

[@KeepitBigBore]

Thanks, you and me both! She'll look good across the back of the defender!!

[@benmaria9359]

@@KeepitBigBore How is the M57 lump holding up, still running a dream!?

[@KeepitBigBore]

Still going strong mate. I’ve put 20k miles on it now and have had nothing but minor teething issues, nothing you wouldn’t expect of a 230k mile engine (oil cooler seal, turbo rebuild are the only things I can think of). As for the Land Rover, again, nothing but usual issues, the transfer case was the biggest problem I had but that was clearly my fault. Done all the wheel bearings and a transfer case rebuild and that’s about it 👍🏽

[@benmaria9359]

@@KeepitBigBore I never really understood why they didn't put the m57 in the defenders from the beginning. Apart from the obvious fact that They used it for the rangey, you think of the strength and torque from a nice straight 6 Diesel. Next best thing to a John Deere!!!

[@KeepitBigBore]

I know, they should have done it for sure. There’s no reason to have it in a Range Rover and not a defender. I think Ineos is taking up the slack and doing what Land Rover didn’t with the grenadier! Your right…but everyone knows a John Deere is no match for a Massey 🤣

[@peterwall9896]

I would love the decompression valve.lol used to nearly take your leg off if you got it on the wrong stroke 😎💕

[@KeepitBigBore]

I know, they are a serious bit of kit to kick over. As digiman said in his comment on this video, a lot of it is down to timing but a lot of it is simply too much compression. The cases break from back fires but a decompression just helps with everything. I actually bought the 85yz490 because the previous owner said he just didn’t have it in him to kick over any of his yz490’s hence why he seemed to be selling them off. It’s a pity that people seem forced to get rid of their pride and joy for that reason!!!

[@larsveldman5374]

Nice two stroke 👍👍

[@kontrolfrkgaming3920]

Nice stand that's epicccc

[@kenmey6803]

I have the IT G 425 I'm putting LEG Lights front and rear so I can ride it on the road but can be put back to factory if some one wants it later. But my power valve it HOLY %$@ crazy. I am worried when on a wet the back tires going to spine and i'l end up on the asphalt .

[@KeepitBigBore]

😂😂😂 I can’t wait to ride this now!!! I agree with the LED lights, very easy to change back if needed, more efficient, brighter, whiter light, just better in every way!!!

[@brantleymyers884]

What is the cylinder head nut tightening sequence?are those flange nuts? If nut and washer how do you get correct torque values?thank you for your time

[@KeepitBigBore]

The sequence is just opposite, I always tighten to half torque all round and then do full torque tightening the opposite nut every time instead of moving around clockwise or counterclockwise. I wouldn't worry too much, it's hard to go wrong with these small heads. I took the torque specs from the manual, I can't remember off the top of my head as every engine I do is different!

[@brantleymyers884]

I appreciate your time and knowledge- I know it's valuable- kl def use that method- awesome video very informative and straight to the point

[@jimallison8374]

I have a 82 IT465 in need of a decompression valve - can you provide the mfg and part number? my kick starting leg would thank you immensely!

[@KeepitBigBore]

I bought that valve from east coast Bultaco in the US but you could probably find other ones. I’ve done a few of these for customers now and I will probably change the valve style soon but this valve works great. Will you do the machining and welding for the decompression yourself?

[@michaelgiglio1571]

Im in Australia. I was wondering how that decomposition valve is activated, by pressing down or vacuum and how much pls . Mike

[@KeepitBigBore]

Hi mate, this one uses a cable with a small lever which I normally mount on the clutch lever side. It’s a short lever that tucks away nicely beside the stop button. You could mount the small lever anywhere you want really. Puts button ones can be used also. I don’t do too many these days but I charged in the region of GBP £125 for the last one I done. Kind Regards Martin

[@michaelgiglio1571]

@@KeepitBigBore ok. Sounds good. I'll think about it. Mike

[@KeepitBigBore]

It’s worth noting as well that some people have used the little push button decompressors on the side of the cylinder head on these bikes, I tried to avoid it purely because I wanted to keep people’s fingers out of the hot fins but it’s That type would be a LOT cheaper to do as it’s just simply drilled and tapped with no welding so it comes down to what people prefer. All that being said, there’s a good chance you’ll find someone in Australia to this for you as the shipping involved from you to me and back would be crazy.

[@eschrader]

What are your thoughts on joining the cases with a hammer vs a crank press?

[@KeepitBigBore]

I think it really depends on the fitment or how tight the bearings are. The only thing that will give much resistance when pulling the cases together is the main crank bearing, the transmission shaft is usually a loose fit. I always choose to pull these together by hand if possible and avoid the crank puller because you have a better feel for any snags. You can see at 1:44 that I couldn’t push the crank into the first half case by hand but after a slight bit of heat it slides right in. Just do the same for the second half case and use a light rubber dead blow hammer with GENTLE taps all round and you’ll be fine.

[@bhenderson7651]

How much to do a head with decompression and squishband if thats an issue like the YZ?

[@KeepitBigBore]

Hello, most people claim to have no issue with squishbands in the IT490 but you'll still hear of people doing it. I'd like to see some pictures of yours if you don't mind. I'm on facebook and instagram as keep it big bore if you want to talk more.

[@Digimanis]

Buddy this problem is classic to this bikes it happenes when somebody is not setting properly the ignition timing and guess what it starts backwards so thats why this problem happens!

[@KeepitBigBore]

I agree!! I’ve seen videos of them running backwards alright. The only reason I know this one happened when he was riding is from the previous owner and the fact that the gears were chewed up by the dog on the kickstart shaft. It ripped chunks out of every tooth on the gear, so he must have been moving. I don’t know how the case survived!!

[@Digimanis]

@@KeepitBigBore they are made from a good aluminum todays bikes brake like glass!!!

[@KeepitBigBore]

They don’t make em like they used to alright!! It’s good business on their behalf I guess, if they made them to last they wouldn’t be able to sell you another bike next year 😂

[@peterwall9896]

...IT 400 nearly killed me in 2002 I just had to sell it 😭👍👍👍👍👍👍👍

[@KeepitBigBore]

Really 🤣🤣 😂 do you want a go on this one when she’s done??!

[@peterwall9896]

@@KeepitBigBore I don't do Facebook or Instagram maybe see you at ace cafe London one Friday night 👍👍👍👍👍👍👍

[@KeepitBigBore]

Absolutely!! I’ll give you a shout if I ever get plan on getting down there!! I want to make a lot more time in the new year for motorbike events and anything a like 👍🏽👍🏽

[@oraldohusbands6394]

Amazing accent, do you have Bajan or Guyanise roots?

[@KeepitBigBore]

😂 thank you! I’m afraid not, I’ve never heard of those places before, I’m half Irish, half African, as you can see, the Irish genes dominate in certain areas 😬

[@rayjones3473]

🤣😅🤣😅

[@rayjones3473]

I get it all the time being a scouser Some people think I'm more exotic than I realy Im 🤣

[@KeepitBigBore]

Someone comment on another one of my videos asking if I was Jamaican or Geordie 😂😂 I thought I sounded 100% Paddy but obviously not…

[@brentwalls2730]

I am neither but Irish and African are a great combination. Phillip Lynott (Thin Lizzy) is my favorite singer. Great video, and engine stand! Thanks for sharing!