A N Other 3TJ 4/6 in the offing

[Kayla850]

The more you ride it the better it gets

Too right! We went out today for quiet potter- Stokesley > Helsmley > Pickering > Whitby (for chips!) > Home. The road from Pickering to Whitby is the awesomest road ever

It didn't miss a beat, which is nice.

Thats very near where I live!
Where abouts are you from??
I am doing a 4/6 build starting in october time and would be great to know somebody local enough who done it before.

We live in Peterlee, SR8. If you have any problems, just ask!

[Kayla850]

Hi Kayla,

I'm trying to finish off a 4/6. Pretty much the same as yours, 3TJ with 4JH engine.

I'm interested in what way you went with the airbox ? Did you mod the 3TJ to fit ?

Mine will be a track/race bike only.

Cheers Pete

Hi Pete,

I was lucky enough to have a complete 4JH to rob bits from, so I used the engine, loom, carbs and headers with the 3TJ airbox eventually. I was going to try and make a large airbox by using the bottom of the tank as the 'lid' and making an ally tray to fit under the carbs but to be honest, I couldn't be bothered- I just wanted to get the bike rideable!

I used a spare 3TJ airbox, removed the rubbers and then enlarged the holes to fit over the 4JH carb bellmouths (where the standard 4JH airbox rubbers would normally fit but I don't have any airbox rubbers fitted- the airbox is a close enough fit and clips over the 4JH carb bellmouths). You can't use the intake trumpet because the tank won't fit properly so I've got a temporary (yeah, right!) solution of gaffa tape holding the filter in. It took a couple of test rides to get the aperture right (I started with a fully open filter entry and ended up with roughly the same intake area as the standard 4JH airbox trumpet). I closed the filter intake up with gaffa tape and folded the ends over to give a rounded profile to help smooth the path into the filter. I'll get a pic later on. The tank still needed to spaced up by 10mm or so, but it works really well and the fuelling feels faultless right through the range and the intake noise is awesome! It's good for an indicated 150mph

I weighed the bike the other day with all fluids, standard battery and around 5l of fuel and it was 167kg. There must be another 10kg hidden there somewhere that can be chopped!

[Evilchicken0]

167 KG wet is a very good weight !!!

So next .... supercharge the engine

[4StrokePete]

Thanks for the info on the airbox. I have some K&N filters, that I will have a crack at tuning on a dyno first. If I cant get them to work, I will go with the 3TJ airbox.

I was also lucky to strip out a complete 4JH. I couldn't believe how heavy the steel frame and swingarm was !!!!

Looking forward to getting it on the track, as I'm sure it will be a blast.

[Kayla850]

Thanks for the info on the airbox. I have some K&N filters, that I will have a crack at tuning on a dyno first. If I cant get them to work, I will go with the 3TJ airbox.

I was also lucky to strip out a complete 4JH. I couldn't believe how heavy the steel frame and swingarm was !!!!

Looking forward to getting it on the track, as I'm sure it will be a blast.

You can see the bits where the 4JH was built down to a budget can't you? The frame weighs a ton! The 3TJ airbox works with the 4JH carbs on standard jetting if that helps at all

[Evilchicken0]

You'll probably find the pods will work on the dyno where the air is still but not so good in the real world where the outer ones will suffer

[4StrokePete]

You'll probably find the pods will work on the dyno where the air is still but not so good in the real world where the outer ones will suffer

Thanks Evil, When I go to the track, I will take the 400 as well. So that if the 600 doesn't work, I still have a ride.
Cheers Pete