Repsol Honda riders Casey Stoner and Dani Pedrosa gave the 'completely new' version of the RC213V a mixed verdict during Monday's post-race test at Mugello.
The new engine and chassis, intended for 2013, was brought to Mugello to be evaluated as a potential race option for later this season.
HRC is battling to overcome chatter and front-tyre squashing issues with the latest Bridgestone rubber, as it seeks to get Pedrosa and Stoner back on terms with Yamaha's title leader Jorge Lorenzo.
The good news for Honda was that both riders liked the new engine. However only Pedrosa preferred the chassis and the Spaniard fell on just his third lap with the new bike due to a downshift error.
“We tested many things today and I'm happy because we found some positives with the new engine and also with the new chassis that can help us in the second part of the season,” said Pedrosa.
“I was really hoping for some improvements after the issues we have had with the extra weight, chattering and the front tyres and in this test we made a step forward.”
Both Pedrosa and Stoner set their best Monday laps on the 2012 bike. As in Sunday's race, Pedrosa was second to Lorenzo, with a best lap just 0.114s slower.
Pedrosa is hoping the new engine, at least, will be ready for the forthcoming Laguna Seca weekend and also seems open to trying the new chassis if available.
The Spaniard is currently 19 points behind countryman Lorenzo with nine of 18 rounds to go.
“Honda is working very hard and I'm sure they will do their best to be able to supply us the new parts for Laguna and the following races, but we'll see if it's possible with the engine allocations; anyway, it would be very good for us,” said Pedrosa.