Does anyone have any details for jet sizes for a 1641 running a standard carb. Only ever fitted 1641’s with twin carbs, but the owner wants to stay stock looking and no one has a recommended main jet size. Cheers
Its 5% bigger capacity. If stock main is 125 then if fuel went through the hole nicely in proportion to jet area then increase of 5% area would correspond to a jet diameter increase of square root of 1.05 giving about 128. Hence lots of mention of people using 127.5... or maybe 130 but that will be 8% bigger area. In other words... not a lot of change needed..
Thanks chaps. The carb came with a 130, so I stuck that in as a starting point. I wouldn’t have thought it necessary either, but Heritage got a bit clucky about correct jetting and warranties, but yet couldn’t offer any advice on sizes.
I have a 1641 and run it with the standard carb and standard jets.......not that I know what size they are but I haven't changed them in the years I have owned it...
I had the same with them when I got a 1641, spoke to their technical people and that wouldn't offer anything solid to ensure warranty is ok. As I would have to rolling road it anyway I just get a pair of 34 ICT's and avoided the problem Sent from my Pixel using Tapatalk
I went through a stage of not using them, but realised all the big companies are basically the same, they all sell the same tat. I’ve not had an issue with returning stuff, but must admit i’ve never returned an engine. I use jk sometimes, but they get orders wrong more often and it’s a pain sending stuff back. Heritage are local, so i’ve gone back to using them mostly for convenience.
They must be aware that folk could put anything on them. They can’t be too fussy, especially if they’re clueless about jetting.
The one I have had for 4 years has been spot on, no issues. I know @Ozziedog had a different experience though Sent from my Pixel using Tapatalk
Heritage offered me an all new engine when I asked last year. They couldnt guarantee a delivery date within 10 weeks so I went to JK for one of theirs that turned up in 3 days. In fact Heritage phoned up a month later to check if I maybe needed an engine. All the warranty on mine says is invalidated if the 120 degC crank case temperature sticker changes colour. Its under the fan housing. So running a bit lean and pushing hard could do this. I cheated and reinstalled a full flow oil filter and cooler, I havent seen over 105 C since...